Six people, five of them children, have died and about 47 others have been injured in a stampede of panicked concertgoers in a small town on Italy’s Adriatic coast, authorities have said.

Three girls, two boys and a woman, who had accompanied her daughter to the disco in Corinaldo, died at the event on Saturday where an Italian rapper was entertaining the crowd. The age of the five child victims, three girls and two boys, ranged from 14 to 16. The mother was 39.

Ancona’s police chief, Oreste Capocasa, told RaiNews24 on Saturday morning that 13 of the injured were in a serious condition. About 800 people were at the event.

Police are pursuing reports that the audience at Sfera Ebbasta’s concert at the Lanterna Azzurra nightclub ran for the exits after someone released a substance similar to pepper spray.

“It is one of the hypotheses which we are verifying,” police commander Cristian Carrozza said. “We have spoken to several witnesses, it is an enormous and complex case, but we can’t say anything more at this stage.”

The tragedy is reported to have occurred as people ran toward an exit that connects the venue to a car park via a footbridge, causing a balustrade to give way.

Police are looking into a witness statement that one of the clubs’s three exit doors was blocked as the concertgoers tried to flee. “We were dancing while waiting for the concert to begin when we smelt an acrid odour … we ran towards the exit but found it locked, a bouncer told us to go back.”

Capocasa denied that the main exit door, which most of the audience ran for, was blocked. “The barriers at the exit fell. People fell and were crushed by the crowd,” he said.

Parents of the victims were at the scene. “We saw bodies lying on the ground, covered in white sheets and a man wandering around as if he was sleepwalking, repeating: ‘My daughter has died,’” a woman whose daughter is among the injured, told La Stampa.

Others at the event also said the stampede was provoked by pepper spray. Raffaele Lerino, a father who had accompanied his daughter to the concert, wrote on Facebook: “A massive jerk threw a can of pepper spray into a room of more than 1,500/2,000, among them me and my daughter of 10 years.”

Ebbasta said on Instagram: “I’m deeply saddened by what happened. I don’t want to pass judgment on who is responsible, but I would just like to ask everyone to stop and think how dangerous and stupid it can be to use pepper spray in a nightclub.”

Pope Francis said during Saturday’s Angelus prayers that he would pray for “the children and the mother who died last night … as well as for the injured”.

The interior minister, Matteo Salvini, speculated on RaiNews24 that the venue might have been over capacity and that regulations within his recently approved security bill would ensure safety rules at nightclubs were maintained.

The minister, who also leads the far-right League, said in a Facebook post that a minute’s silence would be held for the victims before a party rally in Rome on Saturday.

He wrote: “You can’t die like this, at 15, a thought and prayer for the six dead overnight in the Marche region, and hope for the 13 seriously injured in hospital.” He then pledged to “find those responsible for these six broken lives, who due to malice, stupidity or greed turned a party into a tragedy”.

One woman died and more than 1,500 were injured last year when the use of pepper spray provoked a stampede on a square in the northern city of Turin as people gathered to watch the Champions League final between Juventus and Madrid.

The Associated Press contributed to this report