Originally Published: 01 SEP 21 02:16 ET

Updated: 01 SEP 21 02:25 ET

By Aya Elamroussi and Joe Sutton, CNN

(CNN) -- The Caldor Fire, which has forced the evacuation of thousands of people from a popular California tourist town, is now threatening more than 34,000 structures after already destroying hundreds of homes, officials said.

The city of South Lake Tahoe, normally bustling with vacationers, was a gray ghost town Tuesday, with empty parking lots, closed roads and shuttered businesses as the fire's thick smoke hovered over the area.

"Tonight and tomorrow (Wednesday) are critical days," South Lake Tahoe spokesperson Lindsey Baker told CNN.

More than 55,000 people, including some 20,000 South Lake Tahoe residents, have had to evacuate as the massive blaze marches closer to the Lake Tahoe Basin.

"We're just right now trying to see what happens with the structures and businesses in our community and our homes," South Lake Tahoe Mayor Tamara Wallace told CNN.

The fire, which was only 18% contained late Tuesday according to Cal Fire, has burned more than 199,000 acres. And it is expanding at a fierce pace.

"There was a huge amount of granite between the fire and us and I woke up on Sunday and it had, it had jumped that granite and now it is in the Lake Tahoe basin and homes are threatened and our community is threatened and I never thought that was possible." Wallace said.

The mayor praised the evacuation Monday.

"There was a lot of traffic, but we were able to evacuate our city in just five hours, which is good," she said. "We do have a very important holiday weekend. But we have good summers so Labor Day is sort of the last hurrah and, honestly, people's lives are more important than worrying about tourism."

In neighboring Nevada, Gov. Steve Sisolak declared a state of emergency Monday in anticipation of flames crossing state lines in the coming days. California Gov. Gavin Newsom also declared a state of emergency for the counties surrounding Lake Tahoe.

The upcoming days could present more risks as a red flag warning remains in effect for the Northern Sierra Nevada area until Wednesday night. The warning is issued when an area is expected to experience hazardous fire weather that could increase activity.

The area could see gusty winds join forces with extremely dry fuels and low humidity to result in critical fire weather conditions, the National Weather Service said.

"New or existing wildfires will have the potential for rapid spread and growth under these conditions," the service said.

Caldor, which ignited on August 14, has already destroyed 491 homes and 12 businesses as of Tuesday night, according to Cal Fire.

Nearly 40 structures are damaged and five injuries are reported, officials said.

The fire is being fueled by dangerously dry conditions as California suffers through an extreme drought, driven by climate change.

Parts of the Caldor Fire saw dramatic increases in activity early Tuesday morning due to strong winds and low humidity, Cal Fire said.

"The fire continues to back down towards Hwy 50 in multiple locations and continues to threaten control lines [in some areas]," the fire agency noted.

The fire is now California's 17th largest wildfire on record.

13 active fires in California

There are 13 large fires active in California and two more burning in Nevada, according to the National Interagency Fire Center.

California's wildfire season been devastating this year, which saw 1.76 million acres up in flames from 6,913 fires for far, Cal Fire said.

US Forest Service moved to temporarily shutter all national forests in California as resources are stretched this and no relief from the fire-fueling conditions is in sight. Those closures will remain until at least September 17, the US Forest Service Pacific Southwest Region said Monday.

California's largest active blaze -- the Dixie Fire -- has charred 819,956 acres across five Northern California counties over the past 47 days. It was 48% contained Tuesday evening.