LOS ANGELES — A firefighter battling a central California wildfire died Wednesday and another firefighter was hurt when the water tanker truck they were in overturned near Vandenberg Air Force base, officials said.

The accident happened as firefighting crews gained ground in their effort to contain the 19-square-mile fire at the base near launch pads used to send satellites into space.

The truck crashed before dawn at a roundabout on a two-lane highway just outside Vandenberg, said Ventura County Fire Department spokesman Steve Swindle, killing Ryan Osler and injuring Adam Price.

There were no other occupants.

Osler, 38, was a second-generation firefighter whose father worked for the same department. He was married with two children.

Governor Jerry Brown said in a statement that Osler ‘‘dedicated his life to protecting his fellow Californians. This tragedy reminds us of the dangers firefighters face every day.’’

Ventura County was among several departments that sent more than 1,000 firefighters to the fire, which was 45 percent contained.

Firefighters focused Wednesday on the blaze’s southeast boundary. Voluntary evacuation orders were in place for about 400 residents of the San Miguelito Canyon area just off the base near the small city of Lompoc.