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Fans are evacuated from Grant park due to an approaching storm during 2012 Lollapalooza at Grant Park on August 4, 2012 in Chicago, Illinois.
Police evacuated tens of thousands of concertgoers from the Lollapalooza music festival on Saturday before a powerful thunderstorm swept into downtown Chicago and pelted the outdoor venue with rain.
The event was indefinitely suspended at 3:30 p.m. after a severe thunderstorm warning was issued, said police spokesman Darryl Baety.
The estimated 100,000 fans at the sold-out show left Grant Park calmly as they were led to evacuation and shelter sites in underground parking garages along Michigan Avenue.
Day two of the three-day event, which concludes Sunday, was supposed to culminate with the Red Hot Chili Peppers rocking out on the main stage. Concert organizers said Saturday's show would resume if and when it's deemed safe to do so.
"Due to an approaching storm and warnings from the National Weather Service (NWS), Lollapalooza organizers have suspended the festival until further notice," said an announcement on the concert website and sent by text message to those who downloaded the festival smartphone app.
"Lollapalooza officials are continuing to ... monitor weather conditions and determine when the park is safe for festival-goers to return," it said.
Video screens at the venue also displayed evacuation announcements.
Shelby Meade, a spokeswoman for promoter C3 Presents, said the company regretted having to suspend the show.
"Our first priority is always the safety of our fans, staff and artists," Meade said.
Powerful winds from an advancing storm were responsible for last summer's deadly stage rigging collapse at the Indiana State Fair.