An intentional burn meant to prevent wildfire got out of control Friday night in Santa Cruz County, California, and prompted evacuations, authorities said.
The Estrada Fire fire near the rural town of Corralitos had expanded to 150 acres Friday night, with no containment, the California Department of Forestry and Fire Protection said.
"The #EstradaFire is the result of the Estrada Ranch Prescribed Fire," Cal Fire's unit covering San Mateo and Santa Cruz counties unit said on Twitter.
Temperatures in the area were in the low 80s, and light winds at times pointed offshore in the afternoon, according to the National Weather Service. The conditions, including relatively high humidity, didn't meet the requirements for a fire weather watch.
In a statement Thursday, Cal Fire's San Mateo and Santa Cruz unit said the planned 20-acre prescribed burn was necessary "to reduce fuel accumulation and restore and enhance grassland."
"Prescribed vegetation management burns are carefully planned controlled burns that must meet a predefined set of conditions (prescription) in order to achieve ideal fire behavior," it said.
Cal Fire said the fire started at 2:40 p.m. Friday and was spreading at a moderate pace. Structures and power lines were threatened, it said.
Mandatory evacuations were in effect for the Pajaro area, Cal Fire said.
Crews had the blaze surrounded by fire retardant, and the fire might be slowing, the San Mateo and Santa Cruz unit said.
"The fire has died down, and crews will be working throughout the night to strengthen direct control lines," the unit tweeted.