The railing separated concertgoers from the stage at the BB&T Pavillion in Camden, New Jersey, located across the Delaware River from Philadelphia.
The incident happened around 10 p.m.
The 42 injured concert-goers were transported to several local hospitals, according to Camden County fire department and EMS officials. Seventeen of the injured were transported via a mass causality bus, while the remaining 25 were taken by ambulance transports.
Officials said all of the injuries appear relatively minor.
The concert was about halfway finished when the railing collapsed. Concert-goer Christina Kinne tells ABC News there was a lot of commotion following the collapse, and the rest of the concert was cancelled.
ABC News' Brendan Rand and Rex Sakamoto contributed to this report.