A Good Samaritan offered to foot the bill for hotel rooms for 70 of Chicago’s homeless camping out in tents as temperatures dropped to historic lows, with some areas experiencing wind chills of 56 degrees below zero.

The Good Samaritan made the offer on Wednesday after the Chicago Fire Department took away nearly 100 propane tanks donated to the group of homeless people because one of the tanks exploded, the Associated Press reported.

No one had been injured in the explosion, but the fire department decided to confiscate the tanks for safety reasons.

“When we got there, the fire was extinguished and they found all these propane cylinders. That’s when we escalated it to a level 1 hazmat,” Fire Chief Walter Schroeder told the Chicago Tribune.

“There was a significant amount of propane there,” he added. “And with that many cylinders, that’s like a bomb going off.”

City officials told the local Salvation Army about the situation at the homeless encampment, prompting the organization to prepare to move the homeless to a warming center.

An hour after the city placed its initial call the Salvation Army, the city told the nonprofit organization that an anonymous donor decided to place all the homeless people from the encampment in a hotel for the remainder of the week.

The Tribune reported that every person at the encampment except for one person took up the Good Samaritan’s offer. The one person who did not take the offer chose to go to one of the city’s designated warming centers.

Jacqueline Rachev, a spokesperson for the Salvation Army, said the identity of the Good Samaritan is a mystery, but the hotel was somewhere on city’s South Side.