At around 11am Harrison NJ fire fighters responded to 602-606 Frank E. Rogers Blvd on a reported fire. Upon arrival fire fighters found heavy smoke showing from a 2 story wood frame mutliple dwelling.The Kearny and East Newark Fire Departments also responded to assist Harrison fire fighters. Fire was consuming the cockloft of the building and spread to exposures on the Davis St. side of the fire. A third alarm was transmitted bringing Jersey City Ladder 9, Engine 17 and a Battalion Chief to the scene. About 30 minutes into the fire a backdraft explosion occurred causing injury to at least 5 firefighters. The fourth and fifth alarms were transmitted bringing extensive mutual aid to the scene. Heavy fire consumed the cockloft and roofs of several buildings.