Investigators are trying to figure out what started a four-alarm fire in Brooklyn that left six firefighters hurt.

“I got a phone call at work, and someone told me that my house is on fire. It's completely gutted upstairs, really horrible,” said Mill Basin resident Josef Kaufman.

Kaufman is one of several people who lost their homes Monday afternoon when a fire broke out in a multi-family residence on National Drive.

“Flames really started coming out and all this black smoke started billowing out and the whole street was filled with black smoke,” said a resident.

It quickly spread to the building next door.

Firefighters battled the four-alarm fire, from the ground and from the water. Officials say no civilians were hurt. Six firefighters sustained minor injuries.

Firefighters were called at around 2:20 p.m. Crews battled fast moving flames and heavy smoke as it spread to neighboring homes.

“Some significant damage, probably enough where they'll be condemned and torn down,” said FDNY Chief John Sudnik.

“It's one thing to hear about these things happening to people, another experiencing,” said Kaufman.

By nightfall, the Fire Marshal had begun sifting through debris, searching for a cause. Kaufman owns the home next door to where the blaze began. His apartment sustained a lot of water damage. Officials let him inside briefly to grab whatever he could. 

“I have sheets, covers, some pictures I was able to get real quick,” said Kaufman.

Ettie Golasa is a friend of Kaufman's tenant upstairs. 

“I feel very bad for my friends, she just lost her husband two-and-half years ago, and now she has to go through all of this again,” said Golasa. “She lost everything, she lost all her memories, she lost all her pictures, everything.”

Department of Buildings officials are determining if these buildings will have to come down. Meanwhile, the Red Cross is helping those in need of assistance.