CHICAGO — A merciless cold crippled the Midwest on Wednesday, halting planes and trains, shuttering schools and prompting officials in Detroit, Minneapolis and Chicago to open emergency warming centers for the homeless and vulnerable.

The bitter weather was believed to be tied to the deaths of at least eight people, including a man thought to have collapsed after shoveling snow and frozen to death in his Milwaukee garage. Hospitals saw a steady stream of patients reporting symptoms of frostbite.

Temperatures in Minneapolis dipped as low as 28 degrees below zero, with the wind chill reaching 53 degrees below zero, the National Weather Service said. Fargo, North Dakota, reached minus 33; Milwaukee, minus 20. The Midwest was expected to see miserable temperatures through Thursday, and the cold air was moving east.

Across the Midwest on Wednesday, residents who are used to carrying on with life’s routines despite bad weather had little choice but to shiver, stay indoors and make the best of it, even as the insides of their windows became ominously lined with ice.

Even the U.S. Postal Service — despite its unofficial vow that couriers cannot be stopped by “snow nor rain nor heat nor gloom of night” — was forced to suspend deliveries in some particularly frigid places.

Health officials, urging people to go outside only if necessary, warned that exposing skin to the air could lead to frostbite. They were not exaggerating: Going gloveless for only a minute or two, in double-digit negative temperatures, left hands feeling numb, then clumsy and flipper-like, then white-hot with pain.

The most intense cold was expected overnight Wednesday into Thursday, said Ben Deubelbeiss, a meteorologist with the National Weather Service.

After sunset Wednesday, temperatures were to drop again, sinking so low that the record for Chicago — 27 degrees below zero — could be reached.

Some forms of transportation were snarled by the miserable cold. More than 2,500 flights were canceled across the United States, according to FlightAware.

And Amtrak, which ordinarily runs 55 trains to or from Chicago each day, said it had canceled all of its Wednesday services involving the city and that most Thursday trains would also be scratched. Given Chicago’s prominence in the Amtrak network, the decision was expected to be felt across the country.

This article originally appeared in The New York Times.