A group of people using propane tanks for target practice caused a small fire Saturday in Lake County when one of the tanks exploded, CalFire said.

The people believed the tanks were empty and were shooting at them with firearms around 3 p.m., dispatcher Louis Karlow said. The resulting blast started a grass fire of about 2,000 square feet in the 12000 block of White Rock Canyon Road in Upper Lake.

Nobody was injured, he said, and the target shooters were able to extinguish the blaze by the time fire crews arrived.