The seafront platform had been packed with people watching a rap artist at the two-day "O Marisquino" event in the northwest city of Vigo when the accident occurred just before midnight Sunday, the BBC reported.
More than 130 people are being treated for injuries or shock, the Spanish media said.
Some people on the platform, which measured 30m long and 10m wide, fell into the sea, while others started running, leaving personal belongings --mobile phones and handbags -- scattered on the ground, the reports added.
Witnesses reported scenes of panic as people tried to scramble to safety. There was confusion, screaming and crying as several spectators were underage, Efe news reported.
Emergency teams attended to the injured, and divers were sent into the sea to check that no one was trapped beneath the structure, the BBC reported.
Authorities said tracking efforts were on using thermal cameras to ensure none was trapped and an information post has been set up in the Plaza de la Estrella.
Abel Caballero, the mayor of Vigo where the accident happened, said that a probe is on to find out the cause -- was it excess weight or poor structure of the platform -- that led to the crash.
The remaining performances of the urban music event have been suspended.
(This story has not been edited by Social News XYZ staff and is auto-generated from a syndicated feed.)
