LOS ANGELES (Reuters) - A firefighter driving a water-tender truck was killed on Wednesday when the vehicle overturned en route to the scene of a 5-day-old blaze that has scorched a large swath of Vandenberg Air Force Base along the Southern California coast.

The death of Ventura County Fire Department engineer Ryan Osler, 38, marked the second wildland firefighting fatality in California this year, according to the California Department of Forestry and Fire Protection (Cal Fire).

The so-called Canyon Fire, which has scorched more than 12,000 acres of drought-parched chaparral since erupting Sept. 17, prompted the closure of the southern end of the air base to all but essential personnel on Sunday.

It also forced postponement of an Atlas 5 rocket launch scheduled to carry an Earth-imaging satellite into orbit.

As of late Wednesday, firefighters had managed to carve containment lines around 70 percent of the blaze’s perimeter.

According to an accident report by the California Highway Patrol, Osler lost his life while driving his water-tender west-bound toward the fire zone. The rig for unknown reasons struck a curb and rolled over, killing Osler, who was married with two children.

A second firefighter riding in the truck was taken to an area hospital with minor injuries, police and fire officials said.

The cause of the Canyon fire was under investigation.

To date this year, a total of 4,800 wildfires large and small have blackened more than 204,000 acres statewide, nearly 100,000 acres more than at the same time last year, Cal Fire reported.