Crushingly cold temperatures and dangerous wind chills kept their grip on Minnesota making roads slippery and forcing some schools to close.

The temperature in the Twin Cities at 6 a.m.  was 21 below zero, but that was almost balmy compared to other spots in the state.

International Falls reported a temperature of 40 below, Brainerd,  35 below, Ely, 33 below, Roseau, Hallock and Thief River Falls, 24 below,  and Duluth, 19 below.

The National Weather Service wind chill warning will remain in effect through the morning for the north, east central and southeastern parts of the state.  Wind chill values will be as low as 50 below making the risk of frostbite and hypothermia or death very high, the weather service said.

Two deaths in St. Paul this week are being blamed on the bitter cold, authorities said Thursday.

School officials around the state have closed schools. Among them is Bloomington, where on Thursday, biodiesel fuels used in the school buses gelled and clogged filters disabling the vehicles. Students were stranded in the bitter cold.

For a complete list of school closings check

The temperatures will begin to creep back toward 5 degrees above zero as the day goes on.  Tonight, look for freezing drizzle possibly mixed with snow and temperatures of about 11 degrees above by 4 a.m. Saturday.

Saturday will bring a slight chance of snow before noon and high temperatures of around 18 degrees. Saturday night will dip to 10 degrees.

 Rush hour traffic in the Twin Cities this morning was  a repeat of the past few days, when the bitter cold caused black ice conditions on area highways.

Five crashes were reported on the roads at 7:45 a.m. and traffic was slow and congested in all the usual spots. But special mention for frozen motion goes to southbound Hwy. 169 between Interstate Hwy. 694 and Hwy. 62. 

Two people died in traffic accidents apparently caused by the slippery roads. 

A passenger in a pickup truck that slid into oncoming traffic on an icy highway north of the Hastings Bridge and crashed into another pickup died Thursday night, officials said this morning. The crash at 8:30 p.m. on Hwy. 61 injured the two drivers.

Earlier Thursday, a  21-year-old man from Clear Lake, Minn., died in a crash on Interstate Hwy. 94 near Monticello.

Jacob W. Jaeckels died at the scene of the crash about 6:30 a.m., according to the Minnesota State Patrol.

He was driving eastbound on I-94 by himself when he lost control and rolled his vehicle.

He was not wearing a seat belt and was thrown from the vehicle. Road conditions were icy at the time.

Elsewhere in the upper Midwest today, temperatures  were expected to the coldest in years as chilly Arctic air spilled south from Canada.

The bone-numbing blast of arctic air that was also chilling the Northeast had claimed at least three lives and contributed to dozens of traffic accidents as vehicles slipped and slid on icy roads.

Numerous schools in Michigan, Iowa, Ohio and Illinois canceled classes for Friday as officials feared it would be dangerous for students to walk to school or wait for buses.

The National Weather Service predicted the subzero temperatures would persist into the weekend. Wind chill warnings were in effect over much of five states advising the cold and strong winds could lead to hypothermia, frost bite and death.

Iowa City hospitals had treated three people for cold-related injuries by midday Thursday, said University of Iowa Hospitals spokesman Tom Moore. Overnight temperatures there reached minus 24 degrees.

Thursday morning's minus 11 reading — without wind chill — at O'Hare International Airport was the coldest daytime temperature recorded there since 1996, when it got down to minus 14.

The weather system descended from a large, dry air mass that hovered over Alaska and northern Canada for a couple of weeks before moving south. The frostiest conditions were to the north, but the cold stretched as far south as Mississippi, Alabama, Georgia and South Carolina.

In downtown Des Moines, where temperatures didn't top zero on Thursday, the Brenton Skating Plaza closed due to cold weather for the first time since it opened two years ago.

"The reason that we did is with the wind chill factor and how quickly frostbite sets in, and with us being right on the river," general manager Robbin McClelland said. "We want everybody to stay safe."

In Omaha, Nebraska, garbage truck driver James Finley was wearing several layers of clothes to protect himself freezing cold that with wind chill registered minus 15 on Thursday.

"This is the worst in my 13 years," Finley said while taking a coffee break inside his truck.

Officials say at least three people have apparently froze to death overnight.

In Illinois, a 37-year-old man was found dead Thursday in the snow outside his home in Normal — without a coat, hat or gloves. Preliminary tests indicated he was intoxicated.

A 50-year-old man in southeastern Michigan appeared to have frozen to death after being locked out of his duplex overnight.

Earlier in the week, a Wisconsin man froze to death after he apparently went sleepwalking outdoors in bare feet. Authorities suspect he had also been drinking before his body was found Tuesday.