Heat melted the plastic pipe and the line exploded Saturday night with a 15-foot flame.
KREM reports a man who was having a birthday party suffered minor injuries when he was blown into a fence.
Avista utility crews found the fire pit was built on top of the gas line. The man who lives at the house says the pit was there when he moved in.
People are advised to call 811 before they dig anywhere for a free service to locate gas and other utility lines.