An explosion shook the largely deserted streets of downtown Nashville early Christmas morning, shattering windows, damaging buildings and wounding three people. Authorities said they believed the blast was intentional.

Metro Nashville Police Chief John Drake said police were responding to a report of shots fired when they encountered a recreational vehicle blaring a recording that said a potential bomb was to detonate in 15 minutes. Police evacuated nearby buildings and called in the bomb squad.

“Shortly after that, the RV exploded,” Drake said at a midday news conference.

Surveillance video published on a Twitter account Friday that appeared to be recorded from across the street captured an audio recording that included the warning, “... if you can hear this message, evacuate now.” The blast was captured on the surveillance video seconds later.

Metro Nashville Police Department spokesman Don Aaron said three people were taken to area hospitals for treatment, although none were in critical condition. Authorities don’t know whether anyone was in the vehicle when it exploded, however.

Aaron said earlier that some people were taken to the department’s central precinct for questioning but declined to give more details.

The FBI will be taking the lead in the investigation, said spokesman Joel Siskovic. Federal investigators from the Bureau of Alcohol, Tobacco, Firearms and Explosives were also on the scene. The FBI is the primary law enforcement agency responsible for investigating federal crimes, such as explosives violations and acts of terrorism.

At noon, police dogs continued to search cars and buildings in the nearby area.

A Philadelphia man staying in a nearby hotel said that when he heard the blast, he was knew it wasn’t a harmless noise.

“It was a very loud explosion,” said Joseph Fafara. “We tried to rationalize it that it was an earthquake or something. But it was obvious it wasn’t an earthquake.” He said he traveled to Tennessee with his family on Christmas because the state has looser COVID-19 restrictions than Philadelphia.

Fafara went outside to look at the damage but police barricades had already been put in place.

Black smoke and flames were seen early Friday billowing from the area, which is packed with bars, restaurants and other retail establishments and is known as the heart of downtown Nashville’s tourist scene.

uck McCoy, who lives near the area, posted videos on Facebook that show water pouring down the ceiling of his home. Alarms blare in the background and cries of people in great distress ring in the background. A fire is visible in the street outside.

McCoy says he says he heard gun fire 15 minutes before the explosion rocked his building. McCoy said the windows of his home were entirely blown out.

“All my windows, every single one of them got blown into the next room. If I had been standing there it would have been horrible,” he said.

“It felt like a bomb. It was that big,” he told The Associated Press.

“There were about four cars on fire. I don’t know if it was so hot they just caught on fire, and the trees were all blown apart,” he said.

President Donald Trump has been briefed, according to White House spokesperson Judd Deere, who said that Trump, who is spending the holidays in Florida, will continue to receive regular updates. The U.S. Justice Department said Acting Attorney General Jeff Rosen was also briefed and directed all department resources be made available to help with the investigation.

Nashville Mayor John Cooper said the city was lucky that the number of injuries was limited.

Canada's health regulator on Wednesday approved Pfizer’s COVID-19 vaccine, days ahead of possible approval in the United States.

Health Canada posted on it is website that the vaccine made by U.S. drugmaker Pfizer and Germany’s BioNTech is authorized. The vaccine already has been approved by the United Kingdom and Bahrain and officials have said they expect U.S. approval within days.

“This is a critical milestone,” Dr. Supriya Sharma, chief medical advisor at Health Canada.

“Canadians can have confidence in our rigorous review process, and that the vaccine was only authorized only after a thorough assessment of the evidence demonstrated that it met Canada’s strict standards for safety, efficacy and quality.”

Health Canada said terms of the approval require the manufacturer to continue providing information on the safety, efficacy and quality of the vaccine.

Canada is set to receive up to 249,000 doses this month and Canadian officials expect to administer them within days.

Britain on Tuesday began vaccinations with the shot made by Pfizer and BioNTech.

U.S. regulators on Tuesday also released their first scientific evaluation of Pfizer’s COVID-19 vaccine and confirmed it offers strong protection. Vaccines are emerging from an all-out worldwide race and are reaching the market less than a year after the virus was even identified — a remarkable scientific achievement that shaved years off the usual process.

The encouraging developments come as the coronavirus continues surging across much of the world. The scourge has claimed more than 1.5 million lives, including over 285,000 in the U.S., the highest toll of any country. U.S. Food and Drug Administration scientists are meeting on Thursday, when the agency’s independent advisers will debate if the evidence is strong enough to recommend vaccinating millions of Americans.

“It is encouraging to see that our mRNA vaccine is now authorized in Canada. Following U.K. and Bahrain, it is the third country to approve use of our vaccine within a week,” said Sean Marett, BioNTech’s chief business and chief commercial officer.

U.S. FDA scientists reanalyzed data and found the Pfizer vaccine appears safe and more than 90% effective across patients of different ages, races and underlying health conditions.

Health Canada said the vaccine is for use in people 16 years of age or older, but noted Pfizer-BioNTech are running further clinical trials on children of all age groups and that could change.

Canada recently amended the contract with Pfizer so that it would deliver up to 249,000 doses this month. That will mean about 124,500 of the highest risk Canadians will get vaccinated at first as two doses are required per person a few weeks apart.

Pfizer and BioNTech said it will supply a minimum of 20 million doses to Canada through 2021 and as many as 76 million.

Canada has contracts with six other vaccine makers is currently reviewing three other vaccines including one by Moderna that Canadian health officials said could be approved soon.

The government has said 14 distribution centers will be located in large Canadian cities initially. There will be at least one in each province and two each in Canada’s four largest provinces.

“This is phenomenal news for all Canadians as we take the next step toward ending this pandemic. As soon as vaccines arrive on Ontario soil, we will be ready to deliver and administer them,” Ontario Premier Doug Ford said in a tweet.

Also read: UK probing if allergic reactions linked to Pfizer vaccine

A total of 30,000 planned volunteers are ready to take Covid-19 vaccine created by the U.S. government -- one of several candidates in the final stretch of the global vaccine race.

The world’s biggest COVID-19 vaccine study got underway on Monday.

However, there’s still no guarantee that the experimental vaccine, developed by the National Institutes of Health and Moderna Inc., will really protect, reports AP.

After two doses, scientists will closely track which group experiences more infections as they go about their daily routines, especially in areas where the virus still is spreading unchecked, the report says.

NIH’s Dr. Anthony Fauci said “Unfortunately for the United States of America, we’ve plenty of infections right now.”

Moderna Inc. said the vaccination was done in Savannah, Georgia, the first site to get underway among more than seven dozen trial sites in the country.

Meanwhile, several other vaccines made by China and by Britain’s Oxford University earlier this month began smaller final-stage tests in Brazil and other hard-hit countries.

Every month through fall, the government-funded COVID-19 Prevention Network will roll out a new study of a leading candidate -- each one with 30,000 newly recruited volunteers.

The report also said that the massive studies aren’t just to test if the shots work — they’re needed to check each potential vaccine’s safety and following the same study rules will let scientists eventually compare all the shots.

In August, the final study of the Oxford shot begins, followed by plans to test a candidate from Johnson & Johnson in September and Novavax in October.

Meanwhile, Pfizer Inc. plans its own 30,000-person study this summer.

In recent weeks, more than 150,000 Americans filled out an online registry signaling interest, said Dr Larry Corey, a virologist with the Fred Hutchinson Cancer Research Institute in Seattle.

Corey at a vaccine meeting last week said “These trials need to be multigenerational, they need to be multiethnic, they need to reflect the diversity of the United States population.”

He underscored that it’s especially important to ensure enough Black and Hispanic participants as those populations are hard-hit by COVID-19.

Usually, it takes years to create a new vaccine from scratch, but scientists are setting speed records this time around, spurred by knowledge that vaccination is the world’s best hope against the pandemic.

New Jersey police found 17 bodies in one of the state's largest nursing homes after an anonymous tip said a body was being stored in a shed.

A total of 68 people associated with the Andover Subacute and Rehabilitation centres have recently died, with 26 having tested positive for Covid-19.

Police did not find a body in the shed, but said the facility's tiny morgue was "overwhelmed".

New Jersey has over 71,000 cases and 3,100 deaths due to the coronavirus.

Over the weekend, the nursing home had requested 25 body bags from authorities. On Monday, police received the anonymous tip about a body being kept in a shed.

Instead, they found 17 bodies kept in a morgue built to house four.

"They were just overwhelmed by the amount of people who were expiring," Andover police chief Eric Danielson told the New York Times.

It is unclear whether any of the 17 deaths were due to the coronavirus.

Chaim Scheinbaum, a co-owner of the nursing home, addressed the morgue problem in an email to New Jersey Congressman Josh Gottheimer, according to the Associated Press.

"The backup and after hours holiday weekend issues, plus more than average deaths, contributed to the presence of more deceased than normal in the facility holding room," he said.

Mr Scheinbaum also said the facility is adequately staffed.

How big is the problem in care homes?

Seventy-six patients have tested positive for Covid-19 along with 41 staff members between the two buildings, according to the Times .

Thirteen bodies were moved to a refrigerated truck at a neighbouring hospital, while the remaining four were to be sent to a funeral home.

The nursing home owner has since obtained a refrigerated truck for bodies, local media reported.

Prime Minister Justin Trudeau said Saturday that Canada won't bring retaliatory or punitive measures against the United States after the Trump administration announced it would prevent the export of N95 protective masks.

Trudeau said he will speak to President Trump in the coming days. He said his officials are having constructive conversations with American officials. Trump announced late Friday he would prevent the export of N95 protective masks to ensure they are available in the U.S.

The prime minister said he'll tell Trump both countries are interlinked in ways that would hurt both nations if supply chains were cut.

"We are not looking at retaliatory measures or measures that are punitive, " Trudeau said.

 "We know it is in both our countries interests to cooperate."

The prime minister noted Canada ships gloves and testing kits to the U.S and said materials from the N95 masks originate in Canada. Canadian nurses also cross the bridge in Windsor to work in the Detroit medical system everyday.

He noted health care workers rely on the masks in Canada.

Manufacturing giant 3M says there are significant humanitarian implications of ceasing N95 masks to health care workers in Canada and Latin America, where 3M is a critical supplier of respirators.

Ontario Premier Doug Ford said he couldn't stress enough how disappointed he was in Trump for making the decision and Alberta Premier Jason Kenney didn't hold back his outrage at Trump's decision.

"It reminds me of what happened in 1939 and 1940 when Canada was part of the fight against global fascism — the United States sat out the first two or three years and actually initially refused to even provide supplies to Canada and the United Kingdom that was leading the fight at the time," Kenney said.

Canada has more than 12,924 confirmed coronavirus cases, including 214 deaths. Twenty two of those deaths are linked to one nursing home in Ontario. Canada has conducted more than 309,000 tests.