LOS ANGELES, Dec. 5 (Xinhua) -- California's governor declared Tuesday a state of emergency in Ventura County as brush fires destroyed hundreds of homes and prompted tens of thousands of residents to evacuate.

"This fire is very dangerous and spreading rapidly, but we'll continue to attack it with all we've got," said State Governor Jerry Brown Brown in a press release.

Brush fires across the region were fed by extremely high winds, low humidities and dry fuel. Hundreds of fire fighters have been working very hard to minimize damage to property and evacuations are taking place in many places in Southern California, said authorities.

The most dynamic brush fire, dubbed the Thomas Fire, broke out Monday evening in the city of Santa Paula in Ventura County, has burned overnight into the city boundary.

The fire is currently estimated at 50,500 acres (20,437 hectares) without containment. Pushed by powerful winds, the fire has grown dramatically in size within a few hours after it started, threatening the cities of Santa Paula and Ventura, 110 km northwest of downtown Los Angeles.

"Fire crews from many different agencies are actively working on the incident. There are 1,100 fire fighters on scene with additional fire resources enroute," according to Ventura County's emergency information website.

The Federal Emergency Management Agency has granted fire management assistance with the mitigation, management and control of the Thomas Fire.

Another fast moving brush fire, dubbed the Creek Fire, exploded to at least 11,000 acres (4,451 hectares) Tuesday morning in Los Angeles County.

More than 700 fire fighters were battling on the scene, being supported by water-dropping helicopters.

Clouds of black smoke were seen from miles away before being blown by wind. Mandatory evacuations were ordered in nearby areas.

The fire started at several points on hills in early morning and was blown into a raging fire, sprawling along the terrain, according to local residents.

"I was waken up by the sound of fire engines around 5 o'clock in the morning," Derek Berry told Xinhua.

"Watching through the windows, there was a lot of smoke," said Berry, who fled his home immediately to a safe area.

Two of his neighbors' houses were damaged by the blaze, according to Berry.

Fire officials confirmed at least 11 structures had been burned down by the blaze.

"The area had been burned through three years ago in a big brush fire," said Anna Determan, who has lived there for around 32 years.

She said that she would evacuate in accordance with the latest development of the blaze and the change of wind direction because her house is at the foot of the hill and vegetation is exiguous around.

Los Angeles Police Department Chief Charlie Beck urged local residents to evacuate immediately if they were told to leave, noting that strong winds are expected to continue through at least Thursday.

A brush fire, dubbed the Little Mountain fire, broke out in San Bernardino County Tuesday afternoon and grew quickly, prompting mandatory evacuations and burning up at least 100 acres (about 40 hectares).

Ambulances were requested for three burn patients, according to a tweet from the account of the San Bernardino County Fire.