A blaze that burst through windows in a Manhattan apartment building sent 45 people to hospitals, 30 of them being firefighters, fire officials said.

The flames broke out in a third floor apartment in a 26-story building on Grand Street on Manhattan’s Lower East Side.

The smoke made it hard to breathe for the residents of the building.

“The smoke detector and the carbon monoxide alarm started going off. I called the Fire Department maybe 15 minutes later because we couldn’t really breathe. It was really that thick. And they came and got us,” building resident Naomi Pena said, according to Newsday.

Firefighters needed about two hours to bring the fire under control. By that time, 45 people were taken to near hospitals. According to the Fire Department, two civilians have life-threatening injuries, and a third is seriously hurt. All the other victims have minor injuries.

Investigators are trying to figure out what started the three-alarm blaze Thursday evening. Owner of the apartment where the blaze started, Camillo Correida said he came home to find his apartment ablaze, with flames shooting out the window.

“I looked up and I couldn’t believe my apartment was on fire,” he said.

Besides people taken to the hospitals, two other civilians were hurt but declined treatment, firefighters added.