BROOKLYN - A three-alarm fire destroyed six businesses along 86th Street in Bensonhurst this morning and left several firefighters injured. Fire officials say a 911 call came in reporting a large fire raging in the back of a Laundromat at 2384 86th St. The flames then spread left and right, engulfing neighboring storefronts.It took firefighters about an hour and a half to get the flames under control. No civilians were hurt because many of the businesses were closed at the time, but six firefighters were treated for minor injuries and heat exhaustion. Officials inspected the roof of the damaged Laundromat and concluded that the overall structure remains sound. The cause of the fire is being investigated.