The scene outside Lanterna Azzurra nightclub in the town of Corinaldo, Italy. Vigili del Fuoco Last Updated Dec 8, 2018 1:28 AM EST ROME -- Six people, all but one of them minors, were killed and about 35 others injured in a stampede of panicked concertgoers early Saturday at a disco in a small town on Italy's central Adriatic coast, authorities said. A teenage survivor told ANSA that when he tried to flee, he discovered that at least one of the emergency exits was locked. The club was hosting a concert by Sfera Ebbasta, one of the best known Italian rappers, and up to 1,000 people were thought to be inside, BBC News reports. The Lanterna Azzurra club was packed at the time and many of the injured suffered crushing wounds. Twelve of the 35 injured were in serious condition, Capocasa said. The ages of the victims weren't immediately given. It wasn't immediately clear how many people were inside when the stampede erupted or the club's maximum capacity. 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. The report said authorities were investigating if emergency exits were working. © 2018 CBS Interactive Inc. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed. The Associated Press contributed to this report.