A five-alarm fire ripped through five houses early Sunday morning.Firefighters say the fire began around 4 a.m. on the first floor of 509 Concord Avenue then quickly spread to nearby houses. Residents of the house say they do not know how the fire started but left the house after waking to the smell of smoke. Fire officials say 12 firefighters and three residents were transported to the hospital with non-life threatening injuries. The Red Cross reports 48 adults and seven children are now homeless.Three of the five engulfed houses collapsed due to internal damages. Firefighters say a total of eight houses were damaged in the fire by water or broken windows. The cause of the fire is still under investigation but is not believed to be suspicious.