Authorities evacuated approximately 35,000 people from the towns of Superior and Louisville on Thursday as a large grass fire burned throughout Boulder County amid extremely high winds.

The fire, called the Marshall fire, has burned approximately 1,600 acres as of 5 p.m. since it sparked around 11 a.m. at South Foothills Highway and Marshall Road, according to the Boulder Emergency Operations Center, which was activated to respond to the fire. 

The Marshall fire has completely destroyed at least 370 homes in the Sagamore neighborhood in Superior, 210 homes in Old Town Superior and several businesses, including the Element Hotel and a Target store, officials said. 

If initial estimates are correct, the Marshall fire would be the most destructive wildfire in Colorado’s history, behind the Black Forest fire which destroyed 486 homes in 2013. For reference, the Cameron Peak fire – the largest wildfire in state history that burned over 208,000 acres – only destroyed 224 homes.

As of 5 p.m., there have been no deaths reported in connection to the fire. However, Boulder County Sheriff Joe Pelle said it is too soon to tell and he “would not be surprised” if people have been killed by the blaze. One person, a police officer, was injured when his eye was hit by debris. 

Officials urged residents to follow emergency guidelines.

U.S. Rep. Joe Neguse called the fires “unprecedented.”

“Community members should follow guidance from the Boulder Office of Emergency Management and move to quickly evacuate as directed. Everyone in the area should practice the utmost caution,” Neguse said in a statement. “Our office stands ready to assist families, local and state officials in any way that we can. I remain in close touch with Governor Polis and local and federal partners to ensure that every resource is made available to assist our communities in evacuation, fire management and recovery.”

U.S. Sen. Michael Bennett echoed the sentiment. 

“Coloradans, stay safe and follow evacuation orders. We stand ready to help with federal resources,” Bennet said on Twitter. 

In a joint statement, the legislative delegation from Boulder – Reps. Matt Gray, D-Broomfield; Judy Amabile, D-Boulder; Tracey Bernett, D-Louisville; Edie Hooton, D-Boulder; and, Karen McCormick, D-Longmont – called the destruction heartbreaking.

“We are devastated to see the destruction from the fires in Boulder County, and we are heartbroken over the losses so many of our neighbors are experiencing tonight,” they said. “We are truly grateful for the first responders bravely working to save homes and communities, and our prayers are with them and everyone trying to evacuate tonight.”

A second, smaller fire, called the Middle Fork fire, has also been burning near North Foothills Highway and Middle Fork Road since 10:30 a.m. The fire is not threatening any structures and has no size estimate, officials said. 

Gov. Jared Polis declared a state of emergency due to the fires at 3:20 p.m. The declaration allows the state to access emergency funds and provide state resources, including the Colorado National Guard, Colorado Division of Fire Prevention and Control and the State Emergency Operations Center.

The National Weather Service in Boulder said the fires are spreading quickly and called the conditions “life threatening” for people in Superior and Louisville. 

An evacuation order was issued for all residents in Superior just before 1 p.m. Louisville residents were ordered to evacuate an hour later, except for the areas of Old Town and north of South Boulder Road. In addition to official notices, anyone who can see any of the fires is asked to evacuate immediately.

Centura Health said in a late afternoon statement that it had evacuated all patients from Avista Adventist Hospital in Louisville. Patients were either discharged or transferred to Longmont United Hospital or St. Anthony North.

Mandatory evacuations were also issued for Broomfield in the evening for the areas south of U.S. 36 to West 112th Avenue and west of Wadsworth Boulevard. Broomfield’s Skystone neighborhood is under a pre-evacuation order.

Authorities have set up evacuation centers at the North Boulder Recreation Center at 3170 Broadway, the Longmont Senior Center at 910 Longs Peak Ave., the Lafayette YMCA at 2800 Dagny Way and the First Bank Center at 11450 Broomfield Ln. A large animal evacuation site is open at the Boulder County Fairgrounds in Longmont. 

“If you’re in Boulder please stay home and off the roads if you can,” the Boulder Police Department said in a statement. “We know the smoke is making it hard for drivers to see, clogging the roads, while first responders are handling multiple calls.”

At least one of the fires was sparked by downed power lines, which were pushed over by extreme winds in the county, according to the Boulder County Sheriff’s Office.

The sheriff’s office reported two grass fires at 10:30 a.m. in the 5000 block of North Broadway and near North Foothills Highway and Middle Fork Road. The Broadway fire was contained at 1 acre, while the Middle Fork fire is still burning.

All westbound lanes of U.S. 36 and northbound lanes of North Foothills Highway between Nebo Road and Ute Highway are closed due to the fire, deputies said.

The National Weather Service in Boulder said high winds are causing the fires to spread. The area experienced gusts of up to 85 mph throughout the day, but winds are predicted to calm down by Thursday evening, according to the weather service. 

“This is becoming a very high impact wind event for our area, please take it seriously and abide by any evacuation orders from local authorities,” the weather service said in a statement.

Community Foundation Boulder County is collecting donations to support those impacted by the fire at commfound.org.