A stampede of panicked teenagers at a nightclub in Italy, reportedly sparked after an irritant was sprayed, has killed six people and injured more than 50 others.
The dead were three girls and two boys aged between 14 and 16, and a 39-year-old mother who had accompanied her daughter to a rap concert in Corinaldo, near Ancona, on the central Adriatic coast, Ancona Police Chief Oreste Capocasa said.
Witnesses described an irritant, such as pepper spray, being sprayed inside the nightclub, triggering the panic.
Interior Minister Matteo Salvini said there apparently was a "stink" of some irritating substance.
Video broadcast on Italian television showed scores of teenagers rushing out of a door and surging toward a low wall near an exit of the Blue Lantern disco.
The barrier then appeared to give way and a cascade of teenagers tumbled over it, falling on top of each other.
The bodies of the victims were found near a low wall inside the building, firefighter spokesperson Dino Poggiali told Sky TG24 News.
State radio said many of the dead had suffered from crushed skulls.
Survivors said at least one emergency exit door was blocked or did not work.
Mr Poggiali said it was too early in the investigation to know if safety violations might have played a role.
He said that when rescuers arrived, all the doors were open.
Thirteen of the injured are said to be in serious conditions, and 40 others less seriously injured, Mr Poggiali said.
Some of those with minor injuries were treated and released from hospital, he added.
Authorities said the organisers had sold far too many tickets for the space utilised.
Ancona Chief Prosecutor Monica Garulli told reporters at the scene that about 1,400 tickets were sold but the disco has the capacity to hold only about 870 people.
Later, Premier Giuseppe Conte, who visited the scene of the tragedy, said the disco had three rooms but inexplicably only used one of them, with a capacity of 469 people, for the concert.
Firefighters had concentrated on giving first aid to survivors, stretched out on the road outside the club, before starting their investigation, he said.
Italian news agency Ansa said the audience at Sfera Ebbasta’s concert at the Lanterna Azzurra nightclub panicked and ran for the exits after someone sprayed a substance similar to pepper spray.
The Italian rapper - who is popular amongst teenagers - wrote on Twitter that he was "deeply pained" by the tragedy, thanked rescuers and offered his "affection and support" to the families of the dead and the injured.
Out of respect to them, he said he was cancelling some upcoming promotional appearances.
Ebbasta added he did not want to "express judgment" on those responsible but added he wanted everyone to "to stop and think how dangerous and stupid it is to use pepper spray in a discotheque".
Paramilitary police are investigating the cause, in addition to fire officials.