1 person has died after blast at New York City shipyard that also injured 36 people, officials say.

A firefighter and a fire marshal were inside the structure when a second explosion happened, and both were seriously injured by the shock wave from the blast.

“This was a complex, fast-developing emergency situation,” New York Mayor Zohran Mamdani said during a news conference Friday evening.

Multiple people called the fire department around 3:30 p.m., reporting smoke and two workers trapped in the basement of a 150-foot by 150-foot (46 meters by 46 meters) metal structure at the back of the shipyard, Fire Commissioner Lillian Bonsignore said.

Firefighting and EMS crews were on the scene within six minutes. But shortly after they arrived, an explosion occurred, causing serious injuries to multiple fire department members and a couple of civilians, Bonsignore said — including one who died at the scene.

Five firefighters and rescue paramedics were searching for the trapped workers inside, on top of and next to the structure when the second blast occurred, said Chief of Department John Esposito, causing more injuries.

The most serious injuries happened to a fire marshal and a firefighter who were inside and hit by the energy wave from the blast.

“Confined spaces are very dangerous operations for any rescuers,” Esposito said.

The fire marshal is in critical but stable condition with a fractured skull and a small brain bleed, said the fire department's chief medical officer Dr. David Prezant.

“We will be watching him very carefully over the next 24 hours to make certain there is not subsequent brain swelling. As long as there is not, he should do well,” Prezant said.

The firefighter was in serious condition when he arrived at the hospital. But Prezant said he was doing “very well” by Friday evening, and he was being observed to ensure he doesn't have muscle injuries.

The fire was still burning but under control Friday night, with more than 200 firefighters still at the scene, Mamdani said. A comprehensive investigation into the cause of the fire will begin as soon as possible, he said.

Richard Oviogor, who was in the area, told WABC-TV that he heard two explosions and what seemed like a “big shock wave.”

The area is home to several businesses, including a coffee roasting company and a self-storage facility. The shipyard used to be owned by the Bethlehem Steel Company, which built ships for the U.S. Navy during World War II.

Boone reported from Boise, Idaho.