The Deer Creek Fire, which started in eastern Utah and has already destroyed several structures, has crossed the state line into Colorado, state fire officials said Monday night.

At just over 12,900 acres, the fire is bigger than all the other western slope fires combined and is one of several fires that prompted Gov. Jared Polis to issue a disaster declaration on Sunday. Utah Fire Info, a task force comprising state and federal agencies, said the fire crossed into Montrose County, Colorado, around 9 p.m. on Monday and warned that wind gusts of 30 to 50 mph and lightning on Tuesday could spread the fire north, east, and west.

"Today, fire spread modestly across the landscape and slightly east, crossing into Colorado approximately one mile north of highway 46 in Utah, transitioning to highway 90 in Colorado," Utah Fire Info wrote on Facebook.

In the 11 hours or so since crossing into Colorado, the fire increased in size from just over 11,000 acres to almost 13,000 acres, but Utah Fire Info said that crews had contained about 7% of the fire.

Data from InciWeb, an incident management program at the U.S. Department of the Interior, indicates 385 firefighters were working the fire and crews were using dozers, helicopters, over a dozen engines, and at least one airtanker plane.