As temperatures plunged to life-threatening lows this week, more than 100 homeless people in Chicago unexpectedly found themselves with food, fresh clothes and a place to stay after a local real estate broker intervened.

The broker, Candice Payne, 34, said it was a “spur-of-the-moment” decision to help. “It was 50 below, and I knew they were going to be sleeping on ice and I had to do something,” she said on Saturday.

Ms. Payne contacted hotels and found 30 rooms available at the Amber Inn for Wednesday night at $70 per room. Temperatures in Chicago reached lows of minus 25 and minus 26 on Wednesday and Thursday, according to the National Weather Service.

After Ms. Payne paid for the rooms on a credit card, she asked on her Instagram account for anyone who could help transport the homeless people. Soon she had a caravan of cars, S.U.V.s and vans with volunteer drivers.