Organizers were working with emergency management officials to determine if the event could resume on Saturday. The three-day music festival is scheduled to end on Sunday evening.

"Our first priority is always the safety of our fans, staff and artists," said Shelby Meade, communications director for C3 Presents, the promoter behind Lollapalooza. "We regret having to suspend any show but safety always comes first."

The National Weather Service office in Romeoville, Illinois, which covers Chicago, recorded wind gusts up to 55 miles per hour on Saturday and had reports of gusts up to 70 mph, some measured, some estimated, said meteorologist Ben Deubelbeiss.

"Heavy rains, wind and lightning are the main threats from these storms," he said.

The worst of the severe weather powered through Chicago late Saturday afternoon and headed over Lake Michigan and northern Indiana.

Festival-goers were evacuated from Grant Park in downtown Chicago and directed by police and staffers to three shelter sites along Michigan Avenue in underground garages.

The festival draws nearly 200,000 people to the park each year, and this year is headlined by music acts including the Red Hot Chili Peppers, Black Sabbath and Jack White.

A year ago, seven people died and 40 were injured when a huge temporary stage at the Indiana State Fair came crashing down amid high winds just before the country duo Sugarland was to begin performing.

Poor communication about predictions of stormy weather approaching the area ahead of the Sugarland concert was among the factors cited in the stage collapse by consultant studies commissioned by the state.

On Saturday, Lollapalooza organizers were directing fans and the public to check the festival website for updated information.

Lollapalooza, initially organized in 1991 by Jane's Addiction singer Perry Farrell, began as a traveling music festival with several dates all summer. After a six-year hiatus starting in the late 90s, the popular alternative music festival began holding its annual concerts only in Chicago in 2005.

(Additional reporting by David Bailey; Editing by Colleen Jenkins and Bill Trott)

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