Four teenagers escaped a house fire unharmed last evening. Shreveport firefighters got the call just before 5 last night. When they arrived minutes later to the 2200 block of Queens Highway, they found heavy smoke and flames coming from the rear of a one-story wood-frame house. The fire was brought under control just before 5:15. Two crews searched the structure, and were told that all occupants had escaped the home. The four teens say they saw fire coming from an extension cord that was plugged into an air conditioner unit. That room -- along with a car parked near the back of the home -- suffered heavy fire damage. The fire is still under investigation.