Italian police arrested a teenager on suspicion that he may have triggered a deadly nightclub stampede by letting off pepper spray in order to steal jewellery and other valuables from revelers.

The stampede inside the club in Corinaldo in central Italy in the early hours of Saturday claimed the lives of six people – five teenagers and a 39-year-old woman who had accompanied her daughter to a rap concert held at the venue.

They were crushed to death after a metal railing on a concrete exit ramp collapsed, pitching dozens of people to the ground. More than 50 people were injured.

Police detained and questioned a 16-year-old boy who may have set off the spray, leading to panic and the deadly crush, Italian media reported. They also arrested two other minors on drug offences.

Witnesses said they saw a teenage boy try to steal a gold necklace from a young woman in the crowd.

He was identified with the help of videos taken by concertgoers on their mobile phones.