Fire crews have contained a vegetation fire burning off Highway 1 south of Lompoc Thursday afternoon, according to the Santa Barbara County Fire Department.

Capt. David Sadecki said Thursday night that investigators determined the cause was related to a welding and cutting operation.

He said the blaze was reported at about 1:50 p.m. at 6773 Highway 1, one mile south of the highway near Rancho San Julian.

It was fully contained at 3:30 p.m. after burning 6 to 8 acres, Sadecki said.

The fire was burning in a canyon about a mile south of Highway 1, Sadecki said.

About 80 firefighters were dispatched to the incident, assisted by water-dropping helicopters, Sadecki said.

No injuries were reported and no structures were threatened, Sadecki said. Highway 1 remained open.

Cause of the fire remains under investigation, Sadecki said.

The Lompoc Fire Department and Vandenberg Fire Department also responded to the blaze.

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