Thieves stealing copper pipes might have caused a natural gas explosion that destroyed a west-side Indianapolis house. The blast, which happened at about 12:30 a.m. Thursday at 1021 S. Warman Ave., sent debris flying as far as two blocks. The vacant house was being renovated following a fire during the summer. The fire department reported no injuries and briefly evacuated nearby homes until workers could shut off the gas. Police said metal thieves had broken into the house three previous times, and investigators believe the gas and water lines were cut to steal piping.