MARRON VALLEY (CNS) – A wildfire burned across swaths of rugged open terrain in the far southern reaches of San Diego County Tuesday, blackening scores of acres and pushing into Mexico before ground and air crews gained control of the flames.

The blaze — the second to break out in the same general vicinity in as many days — began spreading for unknown reasons at about 10 a.m. near Tecate Creek in Marron Valley, east of Otay Mesa, according to Cal Fire.

By mid-afternoon, the fire had blackened some 40 acres and had moved south across the international line, said Cal Fire Capt. Thomas Shoots.

Ground crews and personnel aboard air tankers and water-dropping helicopters battled the blaze, which posed no immediate structural threats. As of midday, the nearest homes to the burn area were several miles away, Shoots said.

In addition to fighting the flames on the U.S. side of the border, Cal Fire personnel were aiding their Mexican counterparts just to the south in adjacent Baja California territory.

By 5:30 p.m., firefighters had halted the spread of the blaze at an estimated 70 acres in size.

Medics took one firefighter to a hospital for treatment of minor heat- related illness, Shoots said.

The fire was reported about 14 hours after another blaze erupted a few miles to the west, on the outskirts of Otay Mesa. Crews were able to halt the spread of that fire — which caused no known injuries or property damage — by 3 a.m. Tuesday, by which time it had scorched roughly 30 acres, Shoots said.

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