REDDING  (AP) — A 27-year-old man who was allegedly at an illegal marijuana plot is suspected of starting a wildfire that has burned about 6 square miles of forested land in Northern California.

Freddie Alexander Smoke III was arrested Saturday and accused of recklessly causing a fire and with marijuana cultivation, both felonies, according to the California Department of Fire and Forestry Protection.

The agency said he was delivering material to the pot site in Shasta County when the exhaust from his truck ignited dry grass.

The so-called Bully fire has since grown to 3,700 acres and destroyed six structures, CalFire officials said. The blaze, which is burning in steep terrain, was just 10 percent contained Sunday morning.

More than 1,000 firefighters, aided by aircraft, are battling the blaze in hot, dry conditions.

The wildfire had prompted evacuations and road closures, but CalFire said all residents have been allowed to return home and all roads have been open to them.

Still, the fire is threatening 15 homes and about 50 other structures.

In Solano County, a grass fire prompted evacuations in Fairfield and temporarily shut down Highway 12 in both directions. By 4 p.m. residents were allowed back to their homes and most lanes had reopened, officials said.

In Central California, a wildfire has burned nearly 2 square miles (1,200 acres) of a remote wilderness area of the Sequoia National Forest and was just 5 percent contained as of Sunday afternoon, according to the U.S. Forest Service.

Officials said more than 600 personnel are involved in fighting the Nicolls fire, which broke out Friday afternoon south of Sequoia National Park.

No homes were evacuated or in danger.

The forest where the fire started is south of and separate from the Sequoia National Park east of Fresno, which is famous for its giant Sequoia trees.