Workers had expressed concerns about bending or bowed beams and structural issues before a steel airport hangar under construction in Idaho collapsed in January, killing three people and injuring nine others, a newspaper reported.

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Some employees told the site’s supervisor of their worries a day before the privately owned and partially built hangar collapsed Jan. 31 on the grounds of the Boise Airport, according to police reports released to the Idaho Statesman through a public records request.

Meridian-based contractor Big D Builders was the general contractor of the $8.1 million, 39,000-square-foot (3,623-square-meter) hangar for Jackson Jet Center at the airport.

Inland Crane of Boise provided equipment and operators for the project, and that company’s supervisor told police he “has worked a crane on several of these types of sites, and the ‘bowing’ of the beam did not look right to him.”

The supervisor told the police he had reported the concerns to Big D Builders co-founder Craig Durrant, one of three victims in the collapse, and that Durrant said he had made calls to an engineer.

Dennis Durrant, Craig’s brother and company owner, told police in an interview that the beams were “bowing.” They contacted the manufacturer because the supports for the frame weren’t “adequate,” according to the police documents.

An engineer gave them guidance to reinforce the building, Durrant told officers.

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The police interviews indicate Craig Durrant told the crane supervisor that the frame was fine after speaking to the engineer because workers added straps on the beams. They were also trying to place more beams to support the roof.

The Durrant brothers were in the center of the site when they heard loud popping noises, according to the police reports. They ran for the perimeter but Dennis Durrant told police the building “came down within seconds,” killing his brother. Also killed in the collapse were two construction workers, Mario Sontay Tzi , 32, and Mariano “Alex” Coc Och, 24.

Several Inland Crane employees also told their company’s safety officer about “structural integrity concerns” for the hangar, according to the police interviews.

“He also confirmed multiple crane operators from Inland Crane reported curved beams and snapped stiffener cables,” police wrote.

The hangar’s overhead beams were not straight, and there were not enough cross-sections to support the overhead beams, another crane operator told officers.

Yet another crane operator told police the cranes were brought to the construction site to “straighten out the hangar because portions of it were bending.”

A woman who answered the phone Wednesday at Big D Builders said owner Dennis Durrant declined to comment to The Associated Press.

However, David Stark, Big D Builders superintendent general contractor, maintained that there weren’t any problems at the site, and that he didn’t see anything out of the ordinary, the Statesman reported.

Boise police turned its information over to the Occupational Safety and Health Administration, which has said its investigation could take up to six months.

Inland Crane Vice President Jeremy Haener has previously said no action by Inland Crane operators or the crane itself were cause for the structure’s failure, based on the accounts of workers on the site and the steel erecting contractor.

“Inland Crane is actively participating in the OSHA investigation around the tragic incident that occurred on a Boise job site on Jan. 31,” Haener said in a statement Tuesday. “Out of respect for the integrity of that process, we have no additional statements to make until that review is completed.”