Lollapalooza has re-opened after performances were suspended following a storm that hit Chicago.

Organizers of the popular music festival evacuated Chicago’s Grant Park before the storm rolled in.

Word has been filtering slowly to people on the ground, with the Mayor’s office informing fans it’s safe to return to the park before the festival’s organizers.

Festival-goers were treated to a show of thunder and lightning for two and a half hours, from around 3.30pm CST this afternoon. Police and festival staff guided crowds of people from Chicago’s Grant Park to three nearby evacuation sites. While most people ducked away to nearby hotels, bars, and restaurants, one of the evacuation sites was said to be particularly crowded after crowds of people ran in to shelter from the torrential rain.

Grant Park officially re-opened at around 6pm CST, with particularly dedicated fans heading over to wait for festival to re-open after the heaviest part of the storm passed at around 5.15pm.

To compensate for the delay, a large number of events have been cut or moved in the festival schedule. Lollapalooza will also close 30 minutes later to allow more acts to play before the event is forced to close for the night.

The Red Hot Chili Peppers will close the festival with a performance from 9 – 10.45pm on the Red Bull Soundstage. Avicii, Frank Ocean, and Santigold will also play closing sets at other festival stages.

An updated schedule has been released for Lollapalooza 2012 – Click Here to view the updated schedule.