CHICAGO (AP) —  The dangerous cold and heavy snow that hobbled the northern U.S. this week has retreated, but not before exacting a human toll: more than two dozen weather-related deaths in eight states and hundreds of injuries, including frostbite, broken bones, heart attacks and carbon monoxide poisoning.

In Illinois alone, hospitals reported more than 220 cases of frostbite and hypothermia since Tuesday, when the polar vortex moved in and overnight temperatures plunged to minus 30 or lower  with wind chills of minus 50 or worse in some areas.

Hennepin Healthcare in Minneapolis normally sees around 30 frostbite patients in an entire winter. It admitted 18 in the past week, spokeswoman Christine Hill said Friday.

“I definitely saw more frostbite than I’ve ever seen in my entire career just in the last three days,” said Dr. Andrea Rowland-Fischer, an emergency department physician at Hennepin Healthcare.

Most of those patients, she said, had underlying problems that made it difficult for them to take care of themselves: the developmentally delayed, the mentally ill, the very young and the very old. They also included people with injuries related to drugs and alcohol  people who passed out or did not realize they were cold or injured.

“It’s heartbreaking when there are people who can’t take care of themselves and get exposed, just because they either escape from the care that they’re being given or because they’re not being supervised.”

Others got frostbite on their way to work after being exposed to the cold for a short time, often on their hands, feet, ears and face. That included people whose cars would not start or who got stuck outside for other reasons, as well as those who just did not think they could get frostbitten so quickly and went outside without gloves or other protective gear.

Several required “maximal treatment,” admission to the hospital’s burn unit for therapies that include drugs to restore circulation to try to avoid amputations. Some of them will probably still require amputations, a decision usually made by burn doctors four to 10 days after the injury.

Many people decided to stay home even when they were sick to avoid slippery roads and subzero temperatures. In western Michigan, a health care system’s online service saw a major spike this week.

More than 400 people over four days used Spectrum Health’s MedNow to see a nurse practitioner or a physician’s assistant about non-emergency issues, such as aches, rashes, cold and flu, said Joe Brennan, MedNow senior director. Most used an app on their phone. The usual four-day volume is 250.