A construction worker is carried out on a stretcher after being trapped under thousands of pounds of debris for nearly two hours on Tuesday, fire officials said. View Full Caption DNAinfo/Katie Honan

QUEENS — Three construction workers were seriously injured — with one trapped for nearly two hours — as thousands of pounds of construction material fell from the roof of a building and crashed through an Astoria home Tuesday afternoon, the FDNY said.

Construction materials, including laminated beams and bags of cement, were lifted by a boom crane to the roof of the two-story building at 31-25 28th Road, according to FDNY Commissioner Daniel Nigro.

But they were too heavy for the roof, collapsing it and trapping three men working inside, he said.

Fire officials were called to the house at around 3:41 p.m. and found that a 37-year-old construction worker had removed himself from the building soon after the collapse.

A 40-year-old worker was briefly trapped but was removed early in the rescue operation, Nigro said.

But a 28-year-old worker remained trapped under thousands of pounds of construction material for nearly two hours as firefighters, rescue medics and the NYPD's Emergency Services Unit tried to get him out.

Rescuers crawled through the collapsed home to stabilize the trapped worker as other firefighters began digging a trench to get him out, Nigro said

His legs were trapped under the thousands of pounds of materials, and he was kept conscious throughout his removal.

"Rescue medics that work here are able to do things that no one else can do," the fire commissioner said.

"They crawled in there, they administered IV drugs for a crushing injury and pain relief, and kept this person stable as our members dug out these few thousand pounds of material to get this gentleman out."

Third trapped worker removed from Astoria construction site more than an hour after two other men rescued. https://t.co/OG0bq4zy9X pic.twitter.com/lRpIFI1PcK — katie honan (@katie_honan) June 20, 2017

The worker was finally removed just after 5:30 p.m. and taken to Elmhurst Hospital in critical condition, according to the FDNY.

The other two workers were taken earlier to Elmhurst Hospital and also listed in critical condition.

The NYPD was using search-and-rescue dogs to conduct a secondary search for more victims, although it's believed everyone was out of the site, an official said.

Timothy Hogan, the Deputy Commissioner of Enforcement for the Department of Buildings, said the owners of the home had proper permits to build a third-story addition. But construction materials are supposed to be delivered to the ground level, not the roof, he said.

"If materials are delivered to an upper level, it's supposed to have been reviewed by an engineer to make sure the structure they are putting the materials on can handle the weight," he said.

They are currently investigating if the home's owners had this approval.

The owners could not be reached for comment Tuesday.

Neighbor Irene Sanitate, 67, said crews have been working on the home for about two months and were loudly drilling against her wall Tuesday morning.

A few hours later she heard the material fall.

"We were upstairs. It was a big, really loud noise," said Sanitate, who has lived on the block since 1970. "And then a lot of dust."

The neighbor added that she was worried about construction material being placed on the roof.

"The house is old, and when I saw all that material on the roof from day one, I said it's too much weight," Sanitate said. "That was my concern. A lot of cinderblock."