Three people were killed Wednesday when a building under construction collapsed on the property of Boise Airport in Idaho, authorities said. The Boise Fire Department said the building was a “privately owned hangar that was under construction” at the time of the collapse—which also left nine people injured. Five of those hurt were in critical condition, the department said. “Tonight, there was a catastrophic collapse of a metal structure at a construction site,” Boise Fire Operations Chief Aaron Hummel said in a news release. “First responders found a hectic scene and worked to secure and rescue victims.” An investigation into the cause of the collapse is ongoing, the department said.