BISMARCK,Coxno N.D. (AP) — North Dakota Gov. Doug Burgum on Friday declared a statewide emergency in response to an ice storm that felled power lines, leaving more than 20,000 people without electricity around the Christmas holiday.

Burgum also plans to seek a presidential disaster declaration that would free up federal aid to help cover the costs of repairing hundreds of utility poles, his office said in a news release.

More than 4,000 customers remained without power as of Friday, according to PowerOutage.us.

The ice storm was part of a major winter storm that struck the central U.S. earlier this week, causing flight delays and blizzard conditions the day after Christmas.

A powerful, deadly storm also blasted the Northeast before the holiday, causing flooding, power outages and damage to roads and other infrastructure. Elsewhere, high surf hammered the West Coast and Hawaii.

In North Dakota earlier this week, the ice storm forced sections of interstate highways to close, including from Grand Forks to the Canadian border. Police in the capital of Bismarck responded to more than 175 crashes on Tuesday, and roads were so slick in the city that people donned ice skates for fun on neighborhood streets.

Burgum’s statewide emergency declaration directs state government agencies to lend help, if needed, to local and tribal governments, and is key for the governor’s presidential disaster declaration request, according to his office.

State agencies such as the Department of Emergency Services have worked with the North Dakota Association of Rural Electric Cooperatives and utility companies to restore power.

Officials opened an emergency shelter and a warming house in two areas of the state, which has a total population of about 784,000. Burgum’s office asked people to contact local authorities if they need shelter, and to avoid power lines that are down.