Flames broke out at a Fulton Street hardware store Thursday morning before spreading upward in the building and outward to adjacent, vacant structures.

Officials say it began on the first floor of 1163 Fulton St. around 5 a.m., displacing several families and injuring at least one firefighter.

Part of the second floor collapsed, and firefighters say flames engulfed the entire building by the time they arrived.

Neighbors say they helped one another escape harm, but the flames severely damaged the hardware store and another business.

It took more than 150 firefighters nearly five hours to get the fire under control.

"Due to the collapse, it appears that the front and rear walls are starting to bulge, so we have a potential for a collapse of the front and rear walls," says Joe Woznica, an assistant fire chief. 

He also says the fire appears suspicious. 

The American Red Cross says it's providing emergency housing and financial assistance to six families.