A series of Russian missile strikes hit Kyiv overnight Thursday, killing at least six people and leaving 33 others injured, Ukrainian officials said.

The attacks struck 12 sites in the capital’s Darnytskyi, Sviatoshynskyi and Solomianskyi districts, damaging apartment buildings, a medical center and an educational facility. Rescue teams worked through the rubble to locate and free people who were trapped.

In Solomianskyi district, the upper two floors of a nine-story residential building were destroyed, while fires erupted on several lower floors. Residents were also trapped inside two other apartment buildings and a school shelter.

Ukraine’s Emergency Service said the air raid warning remained in place into the early hours of Thursday.

The latest strikes come as Russia has increased its use of ballistic missiles against Kyiv, seeking to put further pressure on Ukraine’s already stretched air defense capabilities. Kyiv has only a limited number of systems able to intercept ballistic missiles, while supplies of ammunition for its U.S.-supplied Patriot systems remain tight.

U.S. President Donald Trump had earlier approved Ukraine’s plans to secure licenses to manufacture Patriot air defense systems, but subsequently withdrew the authorization.

Ukraine has responded by expanding its own long-range attacks on targets inside Russia, including weapons depots, military sites and other strategic facilities, in an effort to disrupt Moscow’s capacity to sustain its strikes on Ukrainian cities.