33 people were hurt at Germany's Rock Am Ring festival when the site was hit by lightning twice.
The first bolt struck the backstage area at 1am on Saturday morning, in Mendig, western Germany, injuring eight production staff.
Lightning-proof tents were opened for campers to shelter before a second bolt struck at 4am, injuring 25 people in one of the campsites.
Local police say the victims were taken to nearby hospitals for observation and no severe injuries were sustained.
Around 90,000 are in attendance at Rock Am Ring, which ended on Sunday with sets from Slipknot, the Foo Fighters, Motorhead, In Flames and others.
Meanwhile, Clutch have pulled out of their planned appearance as a result of "emergency family matters" - but the band vow they'll return to action in time for their club shows in Luxembourg, Belgium and their set at the UK's Download festival on June 12.