Fourteen of the injured were in serious condition, and some 40 others less seriously injured, Poggiali said. Some of those with minor injuries were treated and released from a hospital, he said. Firefighters had concentrated on giving first aid to survivors, stretched out on the road outside the club, before starting their investigation, Poggiali said.
The Italian news agency ANSA said the audience at Italian rapper Sfera Ebbasta's concert at the Lanterna Azzurra nightclub panicked and ran for the exits after someone sprayed a substance similar to pepper spray.
"It was a mess. The bouncers were getting the persons out," one unidentified witness told RAI state radio. "I went out the main door. People fell, one after the other, on top of each other. Absurd."
A 16-year-old boy told ANSA that disco patrons were dancing while awaiting the start of the concert when the stampede erupted. The boy, who was being treated at a hospital, said that at least one of the emergency exits was locked when he tried to flee.
Authorities didn't immediately say how old the victims were, but RAI state radio said the deceased mother was 40, and that about 1,000 people were inside when the stampede began.
Carabinieri paramilitary police were investigating the cause, in addition to fire officials.
- AP