VANDENBERG AIR FORCE BASE, Calif. — Another wildfire, likely sparked by a downed powerline, broke out Wednesday and forced the evacuation of buildings on a large central California military base where another blaze has been burning all week, officials said.

The new fire broke out at 2 p.m. on the north side of the coastal, mostly undeveloped Vandenberg Air Force Base is unrelated to the older, larger fire that’s on the south side, base officials said.

The new blaze, which had grown to at least 100 acres, brought the evacuation of administrative buildings, but was not yet a threat to any of the housing or key facilities on the base.

Southward winds sent smoke over Lompoc, a city of 40,000 people at the edge of the base, though the flames themselves were not threatening the city.

A preliminary report says a downed powerline sparked it.

Resources were being diverted from the earlier fire that broke out over the weekend in a remote canyon and forced the postponement of a satellite launch. It was 70 percent contained and had burned about 19 square miles (49 square kilometers) of rugged land.

A firefighter died Wednesday and another was hurt when the water truck they were in overturned on a highway outside the city of Lompoc, miles from the fire lines.

Ventura County firefighter Ryan Osler was killed, and Adam Price was injured. There were no other occupants in the truck.

Neither fire posed an immediate threat to the base’s launch complex that fires satellites into space.

The two fires forced the cancellation of an exotic car show on the base planned for the coming weekend.

Vandenberg encompasses nearly 156 square miles (405 square kilometers) along the Pacific Ocean.