LOS ANGELES, Sept. 13 (Xinhua) -- Threatened by an aggressive wildfire, authorities of the U.S. state of Utah on Thursday issued a mandatory evacuation order for three communities with more than 5,000 residents.

The fire, dubbed "Pole Creek Fire," was caused by lightning on Sept. 6 inside the Uinta-Wasatch-Cache National Forest, and bolstered by recent high wind, scorching to 20,000 acres (80.9 square kilometers) Thursday evening from 400 acres (1.6 square kilometers) on Wednesday.

According to the press release from the local government, more than 200 crews were assigned to fight the fire, which was reported to converge with another 5000-acre (20.2 square kilometers) wildfire, but high winds hindered fire officials from using air resources like helicopters and planes to fight the blaze.

The Utah Lieutenant Governor Spencer Cox tweeted on his official page Thursday, calling the wildfire situation "a true emergency" for people living in the area and asking them "Please heed all evacuation warnings. Do not take any chances."

Cox also criticized the U.S. Forest Service's response to the fires on Twitter, saying officials made an "inept" decision by managing the fire and letting them burn "during one of the worst droughts in recent history," instead of trying to suppress them.

A press release from fire officials earlier this week said they planned to "confine and contain" the fire and let it burn through heavy vegetation in the area so as to "minimize risk to firefighters" and "enhance wildlife habitat."

Besides of evacuations, several major roadways in the area were forced to close Thursday night, including parts of U.S. Highway 89 and U.S. Highway 6.