Authorities say three adults and an infant were taken to the hospital after a fire at a Boerum Hill apartment building Sunday afternoon.

The fire department was called to the NYCHA house on 178 Bond St. after 4 p.m. Crews arrived to find that a fire had started in a back bedroom on the first floor of the six-story building.

About 60 firefighters were on scene and they had to force themselves inside.

Video captured first responders carrying unconscious people on stretchers out of the building.

"So I was walking home from Target and I saw all the fire trucks. When I got closer, I saw them doing CPR on some guy," said resident Monique Mitchell.

Authorities say the FDNY removed four people comprised of two adult men, an adult woman and a baby from the apartment building.

"They were all in cardiac arrest when they were removed, and we used some other fire resources and we diverted them from putting the fire out to start the CPR before EMS got here," said Fire Deputy Chief Joseph Duggan.

Authorities say first responders were able to get a pulse from the baby and the woman but they were not breathing on their own while the other two remained unresponsive.

"They were all found in various locations trying to get to the front door. The female and the infant were right by the front door after we forced it open and the two adult males were in the kitchen," Duggan said.

All four victims were taken to Brooklyn and Methodist Hospital in critical condition.

Crews were able to bring the fire under control before 5 p.m.

It was not immediately clear what caused the fire as of Sunday night.