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.

Noozhawk executive editor Tom Bolton can be reached at tbolton@noozhawk.com. Follow Noozhawk on Twitter: @noozhawk, @NoozhawkNews and @NoozhawkBiz. Connect with Noozhawk on Facebook.