SAN DIEGO — Six hundred firefighters, aided by helicopters and air tankers, were battling a stubborn brush fire along the U.S.-Mexico border Wednesday that so far has charred more than 2,600 acres of vegetation on both sides of the border.

The blaze, which sparked Monday afternoon in Mexico before crossing into the U.S., south of Dulzura, was reported to be 5% contained as of Wednesday morning, according to Cal Fire officials. Aerial mapping of the burn area estimated total acreage at 2,617 acres early Wednesday. Officials said 1,625 acres were in the U.S. and 992 acres were in Mexico.

One night-flying helicopter worked up until midnight making water drops on the fire, and officials ordered two air tankers and four helicopters to make water and fire retardant drops Wednesday, said Cal Fire Capt. Oscar Sotelo. He said the fire was burning east and was expected to grow after the marine layer burned off.

“The fire did go down in intensity, and they are expecting the intensity to pick up during the day,” Sotelo said.

Although no structures were immediately threatened, the fire is about a mile from Tecate Peak, where radio communications equipment is housed, and a mile from a high-voltage power line that feeds San Diego. Sotelo described the area as being “a pretty rural, inaccessible area.”

Evacuation warnings were issued around 5 p.m. Tuesday for businesses and homes north of Conchera via Road at Cochera via Drive, south of state Route 94, east of Little Tecate Road at SR-94 and west of U.S. Border Patrol Road at SR-94. The Red Cross opened an overnight shelter at the Spring Valley Community Center where residents and their pets were welcomed.

According to Baja California Civil Protection officials, the fire began shortly after 2:15 p.m. Monday near Rancho Las Uvas and the border fence, between Tijuana and Tecate.

Mexican officials on Tuesday had said the fire charred more than 520 acres south of the border and reported it mostly under control there. Sotelo said Cal Fire was told Mexican officials are moving their resources to fight the fire on the east side.

©2026 The San Diego Union-Tribune. Visit sandiegouniontribune.com. Distributed by Tribune Content Agency, LLC.