San Francisco, Jul 7 (IANS): The Salt Fire, a major blaze in Northern California, has continued to rage and has so far scorched 12,430 acres of land with only 20 per cent containment after a week of its eruption, Inciweb, an interstate incident information system reported.

The latest report showed that firefighters are battling the blaze in mountainous areas and providing structure defence in communities nearby, where 41 buildings, including 27 homes, had been damaged as of Tuesday, reports Xinhua news agency.

"Evacuation orders and warnings remain in place for communities near the fire. The fire is very visible from Interstate 5 and firefighters ask the public to be extra cautious when driving in the area," the Inciweb report said.

A community meeting was told Monday that investigators determined the fire was ignited by unspecified hot materials that separated from a northbound vehicle on Interstate 5 and landed in very dry vegetation.

The vehicle remained unidentified.

Residents were also told that the firefighting force was bolstered by resources released from the two other big fires to the north.

Meanwhile, Lava Fire, north of the city of Weed, was 72 per cent contained after burning 25,001 acres, and the Tennant Fire growing slightly to 10,614 acres was 57 per cent contained on Tuesday.