Three workers were seriously injured at a construction site in Astoria after building materials collapsed a roof on Tuesday afternoon, the FDNY said.

First responders received the 911 call about the incident at 31-25 28th Rd. roughly 3:40 p.m., officials said. Crews were loading materials, including beams, concrete bags and concrete blocks, from a boom truck onto the roof when a cinder block was dropped, crashing through the building, according to the FDNY.

One of the workers, described as a 37-year-old man, removed himself from the rubble and was in serious but critical condition, FDNY Commissioner Daniel Nigro said. A second worker, described as a 40-year-old man, was rescued by first responders shortly after and was in critical condition, he said.

First responders worked for over an hour to rescue a third victim, a 28-year-old man, who was trapped under 3,000 pounds of construction materials. During the rescue, paramedics crawled in and administered IV fluids to keep the construction worker stable, according to the commissioner.

All three victims were transported to Elmhurst Hospital Center.

“Today was a beautiful example of people who are willing to risk their lives to save this one individual,” Nigro said at an evening news conference.

advertisement | advertise on newsday

NYPD Deputy Chief Vincent Giordano said he didn’t believe anyone else was in the building and the investigation into the incident was ongoing.

Department of Buildings records show that the city approved a construction permit for the address in April allowing for the conversion of the two-family house into a three family building with a vertical extension.

A permit for a heavy duty sidewalk shed was approved on June 2, 2017, according to DOB records.

With Lauren Cook