According to Philly.com, the incident took place at around 10:00 p.m. when the weight of the crowd pressing against the metal rail seemed to be too much, resulting in it falling over.
A concert-goer caught it all on tape, showing the railing giving in and bystanders falling over into the lower level. Witnesses said about 50 people fell approximately 10 feet onto a concrete slab at the base.
Take a look at the clip, below:
Police and medics took about 42 people to local hospitals to be treated for injuries. The tour, which will run through the summer and end on Sept. 2 is set to hit Mansfield, Mass. later today.