Barrett Junction wildfire
The wildfire burning in the Barrett Junction area has grown to 100-150 acres. Photo via @CALFIRESANDIEGO Twitter

A wildfire northwest of Tecate blackened 4,243 acres Thursday, threatening back-country homes, leveling at least one structure, prompting road closures and forcing evacuations.

The blaze erupted for unknown reasons about 2:30 p.m. off Barrett Lake Road, near state Route 94 in the Barrett Junction area, roughly three miles north of the U.S.-Mexico border, according to Cal Fire.

As of 10:30 p.m., the fire was 5% contained, according to Cal Fire.

Within about 2 1/2 hours, the flames had blackened an estimated 1,400 acres, Cal Fire reported. By then, one structure of undetermined type was known to have been destroyed by the fire.

As ground and airborne crews worked to subdue the fast-moving blaze, deputies evacuated residents in the areas of Barrett Smith and Round Potrero roads, and emergency crews shut down the stretch of state Route 94 between Forrest Gate Road in Campo and Otay Lakes Road in Dulzura, according to the San Diego County Sheriff’s Department.

Fire officials also announced a smoke advisory for Dulzura.

At least 400 homes were under evacuation orders, and the blaze grew to about 1,600 acres by 7:15 p.m., Cal Fire reported. Nearly 600 people were ordered to evacuate, and nearly 800 others were issued evacuation warnings, The San Diego Union-Tribune reported.

Schools in the Mountain Empire Unified and Jamul-Dulzura Union school districts will be closed Thursday, the San Diego County Office of Education announced.

The Tecate Port of Entry was closed due to the fire, U.S. Customs and Border Protection reported.

Temporary shelters for the displaced were operating at the Jamul Casino and Mountain Empire High School in Pine Valley.

Those evacuating large animals were directed by the American Red Cross to go to the San Diego County Department of Animal Services at 5821 Sweetwater Road in Bonita. The San Diego Humane Society is helping with small animal and pet evacuations at Mountain Empire High School at 3305 Buckman Springs Road in Pine Valley.

Updated at 7:50 a.m. Sept. 1, 2022

City News Service contributed to this article.