COATESVILLE, Pa. - September 18, 2012 (WPVI) -- A mother and her young son are dead after heavy flames tore through their Chester County home, and fire officials say the simple devices that warn people of these things, were not working. Fire officials say there were no working smoke detectors inside the home, though neighbors tell Action News that there were working smoke detectors elsewhere in the building. Firefighters were called to the 500 block of E Chestnut Street in Coatesville around 12:30 Tuesday morning. Crews arrived to find heavy flames, which had spread to two nearby homes - a fourth home experienced minor damage. There were reports of people trapped inside, so when crews got to work, rescuing seven or eight people from rooftops. Other people evacuated themselves. But then firefighters discovered the mother and that little boy in an upstairs bedroom. They had already succumbed. he Red Cross is assisting 38 people, including eight children, at a community shelter. Firefighters say they did face some challenges fighting this fire. oatesville Fire Chief Jim Lentz tells us, "There were challenges, absolutely. We were faced with balloon construction in this type of neighborhood, where fire spreads rapidly. There was heavy fire conditions upon arrival with no evidence of smoke detectors. Obviously, smoke detectors are an early indication of fire. And when fire gets this far advanced, it complicates the fire departments operation to provide rescue and suppression operations." An infant and an adult were taken to the hospital. The mother of the infant tells Action News it was done just as a precaution. The adult victim tells us he went because he had some minor smoke inhalation. hestnut Street has reopened and fire crews have rolled out but restoration crews remain on the scene. Residents were able to get back inside to gather a few belongings before houses were boarded up this morning. The cause of this fire remains under investigation.