The Vans Warped Tour was shut down after rapper George Watsky's 12-metre stage jump went dramatically wrong.
The 27-year-old climbed to the top of a lighting truss high above the audience at the London rock festival before attempting to dive into the audience.
Watsky suffered unknown injuries after falling to the floor when the audience reportedly parted to avoid impact.
A female member of the audience also suffered a broken arm after the accident.
Gigwise reviewer Amy Gravelle attended the event and said audience members were completely shocked by the act.
"The band watched in horror as the singer remained on the ground after missing the stage dive," she said.
"He also broke a girls arm in the process and injured other members of the crowd."
The event continued soon after Watsky was taken away in an ambulance.