Witnesses described young clubbers racing for the exits at Lanterna Azzurra, in the town of Corinaldo, after an unknown substance was released into the crowd triggering a stampede.
It's reported patrons tried to quickly leave the disco after someone sprayed a stinging substance
Ancona police chief Oreste Capocasa said about 50 people were injured, 12 seriously.
The victims include five people under the age of 18 - three girls and two boys - and an adult woman who accompanied her daughter to the concert, media reports say. Numerous injured suffered severe bruising while others had broken bones. It wasn't immediately clear how many people were inside when the stampede erupted or the club's maximum capacity.More news: The Gorgeous Nissan GT-R50 Enters Production
The accident happened around 1:00am (00:00 GMT).
Fire brigades said the stampede took place in the Lanterna Azzurra nightclub in the town of Corinaldo, near Ancona, on the Adriatic coast, where rapper Sfera Ebbasta was performing. The boy, who was being treated in hospital, said at least one of the emergency exits was locked when he tried to flee.More news: Cowboys QB Dak Prescott responds to Eagles' trash talk
A 16-year-old boy told ANSA that disco patrons were dancing while awaiting the start of the concert when the stampede erupted.
Asked about survivors' accounts that at least one emergency exit door was blocked or didn't work, Poggiali said it was too early in the investigation to know if any safety violations might have played a role.More news: Airplane skids off runway while trying to land in heavy rain
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