More than 115 acres have burned in Marin County at Samuel P. Taylor State Park, near Lagunitas, Cal Fire said.

Dubbed the Irving fire, it’s threatening 150 homes in the west Marin communities of Forest Knolls and Lagunitas. Forest Knolls residents were ordered to evacuate during the night, according to Marin County Fire.

Cal Fire said Tuesday evacuations were in progress for Upper Lagunitas.

The blaze started about 7 p.m. Monday near the Mount Barnabe fire lookout, according to initial reports. As of Tuesday morning firefighters had contained 25 percent of the fire, which is burning in very steep terrain, the Marin County Sheriff’s Office said.

Samuel P. Taylor State Park is a 2,700-acre redwood and grass oasis in west Marin County that includes old growth redwoods.

Sonoma and Santa Rosa firefighters early Tuesday took two water tenders there to help protect structures.

Check back for updates.

You can reach Staff Writer Randi Rossmann at 707‑521-5412 or randi.rossmann@pressdemocrat.com. On Twitter@rossmannreport.