REDDING, Calif. (AP) — A wildfire in Northern California that authorities say was sparked by exhaust from a truck at a marijuana cultivation site prompted new evacuations on Monday as it kept growing.

It was not immediately clear how many homes were included in the new evacuation order in the rural community of Igo in Shasta County.

Fire officials said the Bully Fire, which started on Friday, was threatening 15 homes after destroying eight homes and 10 other structures. It had burned through 5,500 acres, or more than 8 1/2 square miles, and was 15 percent contained.

Fire crews have been hampered by steep terrain and dry conditions. The National Weather Service recorded highs in the triple digits in the area.

“We have some very, very difficult conditions we’re dealing with,” state fire spokeswoman Teresa Rea said.

About 100 additional firefighters were called in overnight, bringing total personnel on the scene to more than 1,800.

A 27-year-old Sacramento man was arrested Saturday and accused of recklessly causing the fire and with marijuana cultivation, both felonies, said the California Department of Forestry and Fire Protection.

Freddie Alexander Smoke III was delivering material to the pot site when the exhaust from his truck ignited dry grass, authorities said. The Shasta County district attorney has not yet reviewed the case, and it could not be determined if Smoke has a lawyer.

Meanwhile, in Central California containment of a fire in Sequoia National Forest increased to 75 percent after burning more than 2 1/2 square miles.