A three-alarm fire broke out in Chinatown on Thursday night, tearing through a city-owned building that houses multiple nonprofit organizations and a senior center, officials said.

The blaze erupted about 8:45 p.m., engulfing the top two floors of the five-story building on Mulberry Street near Bayard Street, according to the FDNY.

Two firefighters and one civilian were injured. The civilian, an unidentified man, was taken to Weill Cornell Medical Center in serious condition, authorities said.

Witness Jian Chun, 42, said the victim was trapped on the top floor when firefighters arrived.

“They found a guy on the top floor yelling to get out,” said Chun. “They did a great job getting to him. This fire seemed out of control.”

FDNY Commissioner Daniel Nigro said at the scene that firefighters were forced to battle the blaze from the outside due to severe interior conditions.

“The interior became untenable and the units had to be withdrawn,” he said. “It was too dangerous in the building.”

Another witness, Jayden Panice, 37, said “the fire was so intense.”

“The fire department had to pull back because the ladder got engulfed by flames,” said Panice.

The mayor tweeted about the blaze, calling the building “a pillar to the Chinatown community.”

“I know the neighborhood is in shock tonight. We’re going to help the community get through this,” he added.