Three people have died and nine were injured after an under-construction hangar collapsed at Boise airport, in the US state of Idaho, the city’s fire department.
Five of the injured were in critical condition, the fire department said.
Authorities responded at about 5pm Wednesday local time (12am GMT) to the privately owned steel-framed hangar, which suffered a “catastrophic” collapse, Boise Fire Department operations chief Aaron Hummel said.
Everyone who had been at the site had been accounted for as of Wednesday evening, he said.
“It was a very chaotic scene,” Mr Hummel said, describing the incident as a “large-scale collapse” of the framework of the building.
“I don’t know what caused it, but I can tell you it was a pretty global collapse,” he said.
Terra Furman was driving on Interstate 84 at about 5.30pm when she spotted at least 20 police cars, ambulances and firetrucks about a quarter of a mile (400 metres) from the entry to the airport. They were surrounding what she described as a crane folded in half and a building collapsed into the shape of an “M”.
“The walls were still up at a point and the middle collapsed in on either side,” she said.
Mr Hummel said some of the victims were on a hoist or other elevated platform at the time the structure fell, and that required some specialised rescue efforts.
He confirmed that a crane also collapsed in the incident.
Leticia Ramirez, a spokesperson for Saint Alphonsus Regional Medical Center in Boise, said emergency and trauma teams were working with first responders to treat patients who arrived from the scene.
Authorities are investigating what caused the collapse. It happened next to Jackson Jet Center, which offers private airplane charters and maintenance.
Boise city records show the contractor Big D Builders had obtained permits to build a 39,000-sq ft (3,623 sq m) jet hangar for Jackson Jet Center.
The £4.9m project was to include the construction of a concrete foundation and a metal building.
Messages left by phone and email seeking comment from Big D Builders were not immediately returned.
Jessica Flynn, CEO of Jackson Jet Center, said the firm’s “hearts go out to everyone affected by this horrific event”.
Ms Flynn said the collapse happened just west of the existing Jackson Jet Center at a site where the company’s new hangar was under construction. She said dozens of people were working on the site.
“We do not know exactly what caused the hangar collapse,” Ms Flynn said. “Our focus now is on supporting our team and partners during this difficult time.”
James Quintana was driving to the airport when he saw emergency vehicles rushing past him. He said he immediately thought it was a plane crash. He then saw the collapsed hangar and paramedics tending to victims.
“I’m retired law enforcement and when there is that much commotion, that many emergency personnel and vehicles, there is something huge that has taken place,” he said. “It was a scary sight.”
Cody McGowan was working less than 100 metres from the building when he said he heard something that sounded like a loud dog whine.
When he looked up, he saw a hangar as tall as three and a half to four stories tall collapsing in on itself and part of the crane on top.
“When I walked up there, you’re just kind of like, ‘Wow’,” he said. “It’s shocking to see a building falling in on itself.”
Additional reporting by agencies
