LOS ANGELES — Powerful Santa Ana winds fanned the flames of two large wildfires that destroyed some 65 homes and a large mobile home park and put 10,000 people under mandatory evacuation orders.

As 2,235 firefighters were working to contain the destructive Tea Fire that broke out Thursday night in Montecito, an enclave about 90 miles northwest of Los Angeles, another fire erupted overnight Friday in the Sylmar area of the San Fernando Valley.

With wind gusts of 70 miles an hour, the fire in the Sylmar area had burned at least 2,600 acres. Gov. Arnold Schwarzenegger proclaimed a state of emergency, which said more than 65 homes had been destroyed and 100 others had been damaged. The proclamation also said that the area’s electric power supply was threatened. In addition to evacuation orders, roads, including parts of Interstate 5, the primary north-south artery in the state, were closed.

At a morning news conference, Mayor Antonio Villaraigosa of Los Angeles said the wildfire appeared to be the most serious to strike the city in years.

“We know we have lost dozens of structures,” he said, talking loud over the swirling wind. “It is certainly more than we have lost over the last decade.”

More than 600 firefighters were battling the blaze in sustained wind of 20 to 30 miles an hour and gusts reaching 80 miles an hour, hurricane force. The winds were expected to die down in the midafternoon, but the weather was to remain dry and hot, making it difficult to fight the fire.

“These winds are treacherous,” he said. “People really need to understand that because of these winds this fire can be upon you in a moment’s notice.”

There was a glimmer of hope, as the fire approached an area where a fire last year had thinned the brush. But Los Angeles Fire Department Deputy Chief Mario Rueda said blowing embers had ignited smaller fires a quarter mile away from the main blaze, threatening scores of homes.

Three evacuation shelters were opened and Mr. Villaraigosa urged residents to conserve power as the fire marched on major transmission lines that bring power to the city.

A wall of flames surrounded the Olive View Medical Center in Sylmar in the middle of the night, The Los Angeles Times reported, and hospital staff members worked frantically to remove critically ill patients as smoke seeped into the hospital’s ventilation systems and back-up generators failed. Four critically ill babies were sent by ambulance to other centers, and several of the scores of other patients were moved during the night, too, the newspaper’s Web site said.

Fire officials said a mobile home park in the area had sustained major damage. The park is the site of 600 spaces for homes, but no further details were immediately available on the damage.

Capt. Steve Ruda of the Los Angeles Fire Department said the Oakridge Mobile Home Park sustained “almost total devastation.” He said street signs in the park had been melted by flames when 70 mile-per-hour winds blew through the area.

The fire closed major freeways, including Interstate 5, the primary north-south artery in the state.

The Los Angeles Department of Water and Power reported power failures throughout the Valley?? and said they would continue as the fire destroyed transformers and damaged power lines.

Temperatures are expected to rise in to the 80s Saturday in Los Angeles, and high winds are expected throughout the area. Air quality officials issued a smoke advisory for the San Fernando Valley, portions of the San Gabriel Mountains, and the northwest Los Angeles County coastal area.

In Montecito, winds died down overnight, allowing fire crews to get that fire 40 percent contained, said a spokesman for the Montecito Fire Department, Curtis Vincent.

“Things went well over night and we had good progress,” Mr. Vincent said. “There were no additional structures were destroyed. The fire laid down and gave us opportunity to construct that line of containment.”

Mr. Vincent said that a total of 111 homes are known to have been destroyed by the Tea Fire, and that number could rise as firefighters move through the area Saturday morning. He said that 1,500 homes remained threatened Saturday morning. A total of 1,800 acres have burned in Montecito.

“We will be evaluating the fire crews with the idea demobilizing some people to send down south to the Sylmar fire,” he said