Los Angeles, Sep 10 (IANS): As a wildfire in the Angeles National Forest continued spreading, several Los Angeles County cities were under evacuation warnings.

The blaze, dubbed Bobcat Fire, scorched 10,344 acres with sero containment as of Wednesday, Xinhua news agency quoted InciWeb, an interagency all-risk incident web information management system, as saying.

About 400 firefighters and at least four air tanks were sent to battle the blaze, InciWeb said.

However, bad weather hampered the efforts.

"The combination of hot and dry conditions, locally gusty winds, and critically dry fuels will continue to produce critical fire weather conditions across these areas through this evening," InciWeb said.

The Santa Ana winds, forecast to hit the area, are strong, extremely dry down-slope winds that originate inland and affect coastal Southern California in fall and winter.

Tens of thousands of residents living in the cities of Duarte, Bradbury, Monrovia, Arcadia, Sierra Madre, Pasadena and Altadena, which stand along the foothill of Santa Ana Mountain where the Angeles National Forest is located, received evacuation warnings Wednesday morning.

In Arcadia, the city authority on Wednesday announced a state of emergency and encouraged some residents to voluntarily evacuate as a safety precaution.

"The Arcadia Fire Department is fully staffed and is monitoring the situation all clock, with all reserve engines ready should the fire escalate," the city said in a newsletter to residents Wednesday morning.

"We suggest residents affected by the fire to prepare for the evacuation."

Since mid August, fires in California have killed 11 people, destroyed more than 3,600 structures, burned old growth redwoods, charred chaparral and forced evacuations in communities near the coast, in wine country and along the Sierra Nevada.