Investigators have been working to determine what caused the collapse of a steel airplane hangar in Idaho, killing three people and leaving several others badly injured.
Nine other people were hurt, including five who had critical injuries, in Wednesday’s collapse.
The Boise Fire Department said on Thursday morning the scene at Boise Airport had been turned over to Occupational Safety and Health Administration (OSHA) investigators.
The investigation could take up to six months, according to David Kearns, area director for the Boise OSHA office.
“This is a tragedy with a lot of people across the valley grieving today,” Mr Kearns said. “Unfortunately events like these often drive home the importance of ensuring that work site safety and health is a core value at workplaces.”
Fire Department operations chief Aaron Hummel said some of the victims were on a hoist or other elevated platform when the structure fell and that required specialised rescue efforts.
He said the building’s rigid steel frame had been erected and crews were still working on the structural components that would have tied it together when the “catastrophic” failure happened.
“It was a pretty global collapse that occurred, and the main structural members came down,” he said.
Boise fire chief Mark Niemeyer said it had been a “tragic day” for the community and expressed “heartfelt condolences” to those affected.
He also praised first responders “for their quick and professional response rescuing victims and caring for patients in a chaotic and very dangerous environment”.
The hangar is privately owned by Jackson Jet Centre, a charter flight and maintenance company, and work was ongoing on a new building.
Jackson Jet Centre officials said in a statement that they did not know what caused the collapse and “our focus now is on supporting our team and partners during this difficult time”.
