SAN DIEGO COUNTY, Calif. —  A wildfire that originated just south of the U.S.- Mexico border and soon crossed Friday into the extreme southern reaches of San Diego County, has scorched rugged open terrain in the Dulzura area, authorities said.

The blaze began spreading for unknown reasons west of Tecate in Baja California late Friday morning, according to Cal Fire.

Within several hours, the flames had pushed north into the U.S., the state agency reported.

As of 7:10 a.m. Sunday, the fire that had consumed about 100 acres on the American side of the international line and roughly 215 acres in Mexico was 95 percent contained, Cal Fire said.

The blaze posed no structural threats so far.