At least 14 people were hospitalized this week after an explosion at a three-story apartment building in Minneapolis on New Year's Day, according to CNN.

Fire officials confirmed six people hospitalized are in critical condition.

The fire was first reported at approximately 8:15 a.m., local time, at 514 Cedar Ave. in Minneapolis, according to Robert Ball, a spokesman for Hennepin County Emergency Medical Services, who spoke with the Associated Press.

"It's not clear whether people were pushed out of the building from the explosion or whether they fell or jumped out of windows to escape," Ball said.

Rescue workers were affected by the sub-zero temperatures, which made it difficult to put out the flames. Firefighters at the scene said when they tried aiming their hoses at the building, water turned into icicles on the window frames and doorways.

Witnesses said to AP that the façade of the trees and building was coated in a thick layer of ice, making it hard for the 55 firefighters to move around.

"While heat-related illnesses are common for firefighters, now you combine that with the rapid onset of frostbite or hypothermia when they come out and they're wet and exposed to bitter cold temperatures," Ball said.

The fire and explosion caused significant damage to the building. The roof partially collapsed during the incident, according to AP.

The first floor of the building contained a store, the second floor had 10 residential units, nine of which were occupied at the time of the incident, according to Minneapolis Fire Chief John Fruetel.

The cause of the fire is still under investigation.

"This is a Minneapolis tragedy," Mayor R.T. Rybak said in a statement, according to CNN. "This is a Minnesota tragedy. We would like everyone who can help to help."

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