More than 1000 people, predominantly teenagers, were inside the Lanterna Azzurra club, in the town of Corinaldo, attending a concert by Italian rapper Sfera Ebbasta.

Local media reported panic broke out at around 1:00 am local time after a teenager fired pepper spray inside the club.

The concert was yet to commence when an “acrid smell” forced crowds to rush towards the emergency exits, one of which was reportedly blocked.

Railings soon gave way under the pressure and people began tumbling over the barrier.

Five of the victims – two girls and three boys – were between 14 and 16 years old.

The sixth victim was a 39-year-old woman who had accompanied her 11-year-old daughter to the concert.

The injured were taken to hospitals in nearby Senigallia and Ancona, with many suffering crushing wounds and broken limbs.

Seven people are believed to be in a serious condition.

Italian Interior Minister Matteo Salvini said investigators would determine whether overcrowding was one of the causes of the tragedy, as the club had a capacity of under 900.

“From the initial investigation we have verified that more tickets were sold than the place could hold,” Colonel Cristian Corrazza, commander of Ancona province’s paramilitary police, told Italian news agency ANSA.

Salvini vowed that someone would be held accountable for the “six broken lives - whoever out of nastiness, stupidity or greed, transformed an evening of partying into tragedy”.

Italian President Sergio Mattarella demanded “full light be shone on what happened, ascertaining any responsibility and negligence”.

“Citizens have the right to safety wherever they are, in workplaces as well as places of entertainment,” he said in a statement.

“Safety must be assured with special commitment in places where crowds gather, through rigorous inspection and checks. One cannot die this way."

Sfera Ebbasta extended his condolences to the victims’ families on social media on Saturday.

“I’m deeply pained by what happened last night in Corinaldo,” he wrote in an Instagram post.

“It’s hard to find the right words to express the regret and pain [felt] in these tragedies.”

Mayor of Corinaldo, Maurizio Mangialardi, cancelled all events scheduled for the weekend following the incident and ordered the town’s Christmas lights to be turned off.

An emergency phone number was released for those seeking information and assistance related to the tragedy.