An unidentified good samaritan paid for 70 homeless people to be sheltered in a hotel during Chicago’s brutal subzero temperatures. Nearly a dozen tents had set up on a vacant lot not far from Willis Tower and were being heated with propane tanks. One tank exploded and the authorities had to confiscate the rest to avoid a safety risk. City officials notified Jacqueline Rachev, a spokeswoman for the Salvation Army, who began preparations to move people from the camp to the Salvation Army’s warming center. About an hour later, the city called again and said someone someone had offered to put the residents in a hotel for the rest of the week.