A mystery person has paid for hotel rooms for 70 homeless people in Chicago who risked freezing to death in sub-zero temperatures.

The Good Samaritan, whose identity has not been disclosed, paid for rooms for the group of homeless people after Chicago’s firefighters confiscated propane tanks they were using to fuel makeshift heating devices, the Chicago Tribune reported.

Fire Department officials confiscated the tanks after one of them exploded, saying they posed a safety risk.

But that decision risked costing the homeless group their lives. Chicago has been gripped by a cold snap which has sent temperatures down to as low as -32C. The polar vortex means the US city is currently colder than Alaska or the North Pole.

The Good Samaritan then stepped in to save the day.

“Some wonderful citizen is going to put all of them up at a hotel for the rest of the week,” a Salvation Army representative said.