(CNN)A rapidly growing wildfire prompting mandatory evacuations in northern Colorado is threatening to merge with the state's largest wildfire in history, fire officials said.
Colorado officials are warning that two major wildfires could merge
The Rocky Mountain National Park closed Thursday, and mandatory evacuations were issued for parts of Estes Park, as firefighters continue battling the East Troublesome Fire.
The blaze started on October 14 but grew over 100,000 acres Wednesday night. The growth of the fire equates to roughly 70 football fields of forest burned every minute, according to CNN meteorologist Brandon Miller.
As of Thursday, the East Troublesome Fire had burned about 170,000 acres and was only 5% contained, fire and forest officials said.
Incident Commander Noel Livingston said Thursday afternoon the fire's growth is "really unheard of for a fire in this part of the world, in timber."
Fire officials warned on Thursday that it could merge with the Cameron Peak Fire, the state's largest wildfire on record, which is about 55% contained.
There is only about 10 to 15 miles between the two wildfires, said Stan Hilkey, the state's public safety executive director.
"We are doing everything we can to save lives and save homes," Colorado Gov. Jared Polis said in a news conference on Thursday.
The East Troublesome Fire, located near Grimes Peak in the Arapaho National Forest, had jumped the Continental Divide and was burning the upper reaches of the Rocky Mountain National Park, the National Weather Service in Boulder tweeted.
Officials in Grand County, about 65 miles west of Boulder, Colorado, issued mandatory evacuations in response to the fire, which has intensified significantly.
"#EastTroublesomeFire continues to advance towards Grand Lake. IF YOU LIVE IN THIS AREA, EVACUATE IMMEDIATELY!! Fire has been reported as close as Columbine Lake," the National Weather Service in Boulder tweeted Wednesday night.
"The fire is growing faster than we can catch it right now," Fire Incident Commander Jake Winfield said Wednesday, according to CNN affiliate KCNC.
And even though nearly 300 responders are on the front lines battling the fire, weather conditions throughout Thursday will be ideal for wildfire development. High winds that have already been fanning the flames will pick up, dry conditions will continue and temperatures will be warmer than normal.
"The longer the day progresses, the worse the conditions will get," said CNN meteorologist Michael Guy. A cold front approaching the area Thursday evening will offer little relief, Guy said, and instead will be followed by wind gusts of up to 50 mph.
But a stronger front pushing south this weekend will bring some of the coldest air this season. Snow and higher humidity are forecast, which should offer some hope for containment, he added.