Gwinnett County firefighters are still trying to determine what caused a blaze Wednesday at a house on Chapel Estates Lane in Dacula.

An adult woman and a child were at home when they heard a loud explosion at 4:28 p.m. and saw their deck engulfed in flames, said Gwinnett fire Capt. Thomas Rutledge. They escaped unharmed.

Firefighters arrived to find the back side of the house engulfed in flames. The fire was brought under control by 6 p.m., but the house was a total loss. The American Red Cross assisted a family of four displaced by the damage.