BROOKLYN - Four people were hurt and several tenants displaced after a two-alarm fire in Bed-Stuy. 

The fire chief says it started on the second floor of a three-story apartment building on MacDonough Street at around 8 a.m. Thursday. 

When firefighters arrived, flames were coming out of the windows, but they were able to get it under control in about a half hour. All residents, including a mother with seven children who lived on the second floor, were able to evacuate themselves.

Three tenants suffered minor injuries and one firefighter twisted his knee while helping to put out the blaze. 

Investigators are trying to determine the cause.