SOUTH LAKE TAHOE, United States (AFP) — Thousands of people were ordered to evacuate Monday as a huge wildfire loomed down on a major US tourist spot, filling the air with choking smoke.

The Caldor Fire has already torn through more than 270 square miles (700 square kilometers), razing hundreds of buildings.

On Monday it was roaring towards South Lake Tahoe, the main resort town in the popular holiday area that straddles the California and Nevada border.

“The firefighting conditions, the fuels, are historic,” said Cal Fire Incident Commander Jeff Veik, according to the San Francisco Chronicle. “We will put this fire out. It’s not going to be today.”

The western United States is burning at an alarming rate, with over 2,700 square miles blackened by late August — more than double the area consumed by this time in an average year.

The fires are being driven by a historic drought that has left swathes of the region parched, as man-made climate change takes a visible — and painful — toll, and people living in the area are forced to flee.

“I got a knock at 10 pm last night with a warning to be ready,” South Lake Tahoe resident Corinne Kobel told the Sacramento Bee newspaper.

“At 10 am this morning, it was the sheriffs kicking us out. I am freaking out.”

Kobel was among the 22,000 people ordered out of their homes on Monday morning, joining tens of thousands of others who have been forced to flee by the fire’s relentless march.

An AFP journalist witnessed streams of traffic leaving the city, with cars and RVs clogging the main roads.

On Sunday as the fire tore through the Twin Bridges area, there were incongruous scenes as flames raged around ski lifts.

The Caldor Fire began on August 14, and quickly spread through the Eldorado National Forest.

Smoke from the blaze has been threatening tourist spots around Lake Tahoe for a week, filling the air with a choking haze.

The alpine lake is known for its clear waters, and the areas surrounding it boasts spectacular scenery, including some of the most popular winter sports resorts in the western United States.

The blaze is one of scores across the region that are stretching the resources of local firefighters.

Further north, the huge Dixie Fire has ripped through more than 1,100 square miles in the six weeks since it erupted.

Thousands of firefighters and other emergency personnel are involved in battling the fires, which are fanned by gusting winds and fed by tinder-dry fuel.

© Agence France-Presse