The latest in a spate of recent wildfires in the far southern reaches of San Diego County spread over remote, hilly terrain Friday just north of the U.S.-Mexico border.
The blaze erupted for unknown reasons about 1 p.m. near Doghouse Junction on the eastern slopes of Otay Mountain, a few miles from the international line, according to Cal Fire.
Ground crews and personnel aboard air tankers and water-dropping helicopters battled the blaze, which blackened 10 to 15 acres within an hour, said Thomas Shoots, a fire captain with the state fire agency.
The flames posed no immediate structural threats, Shoots said.
The blaze was the 19th to break out in the southern border region of the San Diego area this year, according to Cal Fire. Most have occurred in the last several months, including two earlier this week.