Colorado’s East Troublesome Fire, the second-largest fire in state history, roared through timber stands and rugged terrain in Rocky Mountain National Park amid high winds Saturday, threatening the tourist town of Estes Park to the east as officials mourned the deaths of an elderly couple who tried to ride out the blaze at their home near Grand Lake.

The fate of Estes Park became a race between fire and ice, as a snowstorm due to hit Saturday night and last into Sunday is likely to halt the fire’s spread. Crews were still in a “very aggressive firefight” Saturday evening, officials said, trying to keep the blaze from lodges and homes in the town of about 6,500. Eastern areas of Estes Park are now under evacuation orders — the western side was evacuated Thursday.

“We will do everything in our power to protect the town of Estes Park and every community that is threatened by these historic fires in our state,” Gov. Jared Polis (D) tweeted Saturday afternoon, as more than 3,000 firefighters joined Colorado National Guard members to stem the blazes’ spread.

The town came under siege during an especially severe Colorado fire season, which has stretched longer than any in modern memory and spawned the state’s three largest fires on record. The two biggest, East Troublesome and the Cameron Peak Fire, are still burning, and the entire state is mired in drought conditions for the first time since 2013.

Water, electric and fiber-optic communication systems remained “safe and stable” late in the afternoon, town administrator Travis Machalek said in a video update. But fire officials had asked to shut off electricity in parts of Estes Park as a precaution, with the fire so close.

“Conditions will continue to change constantly,” Machalek said, warning, “We cannot become complacent.”

Earlier in the day, high winds kept firefighting aircraft from flying, and authorities used satellite imagery to locate the blaze. “We’ve got a heck of a day ahead of us,” said Paul Delmerico, the operations section chief on the fire, in a morning video briefing.

Red flag warnings are in effect for the Rockies as low humidity combines with high winds to create “critical” fire weather, the second-most severe category on the fire risk scale. The National Weather Service’s Denver/Boulder forecast office said late afternoon that there were signs of “increased fire activity” west of Estes Park.

The Cameron Peak blaze, located just a few miles from the East Troublesome fire and the state’s largest on record, is also expanding Saturday, satellite heat detections show. There is even a possibility the two fires could merge before the cold front settles the blazes at night.

At higher elevations where the fire is especially active, snowfall amounts later this weekend are forecast to exceed a foot, which will lead to the odd juxtaposition of a flame-filled surface and snow-covered trees and ground areas.

“Imagine a foot of snow over those hot fires!” wrote the National Weather Service’s local forecast office wrote Saturday morning. By Monday, temperatures in the fire area are expected to be in the single digits to below zero Fahrenheit, though it’s not clear if this will be enough to completely extinguish the blaze.

By midday, officials had some hopeful news: Crews on the north end of the Cameron Peak Fire reported some snowfall in the area. Later, authorities said they were expecting “intermittent precipitation” on the fire starting in the evening and going steady after midnight.

Dual threats from fire and snow point to the rarity of high altitude blazes at this time of year in Colorado, when winter typically settles in. No fire on record in Colorado that has started this late in the season has become nearly as large, putting the blaze in uncharted territory and showing all the signs of climate change.

The East Troublesome Fire has been so severe it jumped the continental divide, a span of two miles that contains mainly rocky terrain. The fire grew an astonishing 140,000 acres in size between Wednesday afternoon and Thursday, and stood at 188,389 acres as of Saturday afternoon.

According to Nick Nauslar, a predictive services meteorologist with the National Interagency Fire Center (NIFC) in Boise, Idaho, having a wildfire jump the divide has happened in other fires before but is an extremely rare occurrence.

Colorado’s fires are raging during a severe drought, aggravated by record heat, through stands of trees killed or weakened by years of a bark beetle infestation. The harmful beetles are a phenomena linked to climate change that is occurring across vast stretches of the West and into Canada.

Higher temperatures in Colorado have given once-scarce pests, formerly held in check by extremely cold winter temperatures, an opportunity to spread and damage or destroy trees. Studies have shown that in some ecosystems, these dead or weakened trees can accelerate blazes, although in others they may actually slow down some wildfires.

Long-term climate change trends may be playing a significant role in the fires, scientists say. According to a 2016 study, human-caused climate change nearly doubled the area burned in western states, mainly by making the region hotter and drier.