A power line mishap caused last weekend's so-called Shekell fire that charred some 13,500 acres in the Moorpark area, investigators said.

Ventura County Fire Department officials said power lines ignited the fire, but it's still unknown what sparked a second blaze that merged with the Shekell fire after flaring up hours later nearby.

Some 8,100 Southern California Edison customers lost power the day of the fire.

But Edison spokesman Steven Conroy said the lines may belong to other providers and that there are privately operated lines in the area as well as those maintained by Edison.

Firefighters had the blaze surrounded by Tuesday. Crews are expected today to leave the command center in Arroyo Vista Park set up to deal with the fire.