Cal Fire crews at the scene of the Springs Fire. Courtesy Cal Fire

A fire of unknown origin blackened about three acres on a brushy hillside next to Interstate 15 in northern San Diego County Friday, moving dangerously close to homes but causing no reported structural damage or injuries.

The blaze near on the west of the freeway near Deer Springs Road in the unincorporated Escondido area erupted shortly before 12:30 p.m., according to Cal Fire.

Ground crews and personnel aboard emergency-services helicopters and air tankers worked to corral the flames and keep them away from nearby houses, getting the spread of the fire halted within about an hour, said Issac Sanchez, a fire captain with the state agency.

The blaze forced the closure of one lane on the southbound side of the interstate and caused heavy congestion in the area through the afternoon, the California Highway Patrol reported.

The cause of the fire was under investigation, Sanchez said.

— From Staff and Wire Reports