"There were a lot of bands I wanted to see so I hope they find a way to reschedule those shows," said Jean Compton, 20, of Lincoln Park, who looked forward to performances from Alabama Shakes and The Tallest Man on Earth.
Some of the people who evacuated to the North Grant Park Garage said they went there on their own, without guidance from festival staff.
Alicia Fuentes, 27, visiting from San Francisco, Said she evacuated to the garage only because her car was parked there.
"All they said was 'move now, move now,' no directions. Nothing. We didn't even know what was going on until I called my mom," Fuentes said. "She said there are severe thunderstorms coming through, you better go underground."
Most of the fans evacuated quickly but some initially refused to go, even as the sky darkened.
"Were not leaving," said Ashley Dunne, 21, at about 4:15 p.m., about 45 minutes after the festival was suspended.
Loren Santow, 56, and his wife were stretched on a now-empty bench.
"It doesn't feel like an emergency situation is imminent," he said. That changed by 5 p.m. or so.
As the storm hit, at least one man aboard a 34-foot sailboat who was about a quarter mile off Montrose Harbor could not make it in, according to a police Marine Unit officer.
Several residents in nearby high-rises saw he was struggling and called to alert authorities.