Light from a high afternoon sun slanted through the tall windows of the weathered wooden church, catching on the plank floorboards and illuminating the stained glass. Outside, the arid ground of the northern New Mexico foothills stretched for miles — a picturesque setting for an Old West gun battle.

The actor Alec Baldwin, haggard in a white beard and period garb as he played a wounded character named Harlan Rust, sat in a pew, working out how he would draw a long-barreled Colt .45 revolver across his body and aim it toward the movie camera.

A crew readied the shot after adjusting the camera angle to account for the shadows. The camera wasn’t rolling yet, but director Joel Souza peered over the shoulder of cinematographer Halyna Hutchins to see what it saw.

Souza heard what sounded like a whip followed by a loud pop, he would later tell investigators.

Suddenly Hutchins was complaining about her stomach, grabbing her midsection and stumbling backward, saying she couldn’t feel her legs. Souza saw that she was bloodied, and that he was bleeding too: The lead from Baldwin’s gun had pierced Hutchins and embedded in his shoulder.

A medic began trying to save Hutchins as people streamed out of the building and called 911. Lighting specialist Serge Svetnoy said he held her as she was dying, her blood on his hands. Responders flew Hutchins in a helicopter to a hospital, to no avail.

A week after the Oct. 21 shooting on the set of the movie “Rust,” accounts and images released in court documents, interviews and social media postings have portrayed much of what happened during the tragedy, but they have yet to answer the key question: how live ammunition wound up in a real gun being used as a movie prop, despite precautions that should have prevented it.

During a news conference Wednesday, Santa Fe County Sheriff Adan Mendoza said there was “some complacency” in how weapons were handled on the set. Investigators found 500 rounds of ammunition — a mix of blanks, dummy rounds and what appeared to be live rounds, even though the set’s firearms specialist, armorer Hannah Gutierrez Reed, said there should never have been real ammo present.

Read: Crew member: Baldwin careful with guns before fatal shooting

“Obviously I think the industry has had a record recently of being safe,” Mendoza said. “I think there was some complacency on this set, and I think there are some safety issues that need to be addressed by the industry and possibly by the state of New Mexico.”

Mike Tristano, a veteran movie weapons specialist, called it “appalling” that live rounds were mixed in with blanks and dummy rounds.

“In over 600 films and TV shows that I’ve done, we’ve never had a live round on set,” Tristano said.

The shooting occurred on Bonanza Creek Ranch, a sprawling property that bills itself as “where the Old West comes alive.” More than 130 movies have been filmed there, dating back to Jimmy Stewart’s “The Man from Laramie” in 1955. Other features have included “3:10 to Yuma,” “Cowboys and Aliens” and the miniseries “Lonesome Dove.” The Tom Hanks Western “News of the World” and “The Comeback Trail” starring Robert De Niro, Tommy Lee Jones and Morgan Freeman were filmed there in recent years.

Workplace disputes beset the production of “Rust” from its start in early October. In the hours before the shooting, several camera crew members walked off the set amid discord over working conditions, including safety procedures. A new crew was hired that morning, but filming was slow because they were down to one camera, Souza told detectives.

At 24, Gutierrez Reed had little experience working as an armorer. She told detectives that on the morning of the shooting, she checked the dummy bullets — bullets that appear real, save for a small hole in the side of the casing that identifies them as inoperable — to ensure none were “hot,” according to a search warrant affidavit made public Wednesday.

When the crew broke for lunch, the guns used for filming were locked in a safe inside a large white truck where props were kept, Gutierrez Reed said. The ammunition, however, was left unsecured on a cart. There was additional ammo inside the prop truck.

After lunch, the film’s prop master, Sarah Zachry, removed the guns from the safe and handed them to Gutierrez Reed, Gutierrez Reed told investigators.

According to a search warrant affidavit released last Friday, Gutierrez Reed set three guns on a cart outside the church, and assistant director Dave Halls took one from the cart and handed it to Baldwin. The document released Wednesday said the armorer sometimes handed the gun to Baldwin, and sometimes to Halls.

Read: Alec Baldwin fired prop gun on set, killing cinematographer

Gutierrez Reed declined to comment when contacted by The Associated Press on Wednesday. She wrote in a text message Monday that she was trying to find a lawyer.

However Halls obtained the weapon before giving it to Baldwin, he failed to fully check it. Normally, he told detectives, he would examine the barrel for obstructions and have Gutierrez Reed open the hatch and spin the drum where the bullets go, confirming none of the rounds is live.

This time, he reported, he could only remember seeing three of the rounds, and he didn’t remember if the armorer had spun the drum.

Nevertheless, he yelled out “cold gun” to indicate it was safe to use.

“He advised he should have checked all of them, but didn’t,” a Santa Fe County sheriff’s detective wrote in the affidavit released Wednesday.

It’s unclear whether Baldwin deliberately pulled the trigger or if the gun went off inadvertently.

In the commotion after the shooting, Halls found the weapon — a black revolver manufactured by an Italian company that specializes in 19th century reproductions — on a church pew.

He brought it to Gutierrez Reed and told her to open it so he could see what was inside. There were at least four dummy bullet casings, with the small hole in the side, he told detectives.

There was one empty casing. It had no hole.