LOS ANGELES, July 19 (Xinhua) -- A wildfire, coded "Detwiler Fire," raged to 45,000 acres Wednesday outside the Yosemite National Park, causing an evacuation of 4,000 residents.

The blaze started Sunday near Lake McClure and was only 7 percent contained by Wednesday afternoon, according to the California Department of Forestry and Fire Protection (CAL FIRE).

More than 2,200 firefighters together with a crew from the Southern California city of Lompoc were fighting the blaze.

About 4,000 people have been evacuated under a state of emergency issued by California Governor Jerry Brown Tuesday, including the entire city of Mariposa, a few miles west of the park, 440 kilometers north to Los Angeles.

Video clips posted by FOX 13 showed that downtown Mariposa of 2,000 residents with century-old wooden buildings, was empty except for firefighters and other emergency workers. Fierce flames were visible on slopes about a mile away.

"You couldn't even see the sun in the ash-filled sky", said Tony Munoz, a school custodian who was among those evacuated from Mariposa told FOX 13.

Yosemite National Park is still open, park spokesman Scott Gediman said Wednesday, but the fire closed one of several roads into the park.

Moreover, due to the heavy smoke blowing in from "Detwiler Fire," an air quality alert was issued Wednesday for the Reno-Sparks area in Nevada state, more than 150 miles (241 kilometers) away.

The wildfire, named for one of the roads in the area, is one of 17 large wildfires burning in California on Wednesday, CAL FIRE said.