At least 20 people, including children, were injured after a fairground ride collapsed in Italy, officials say.

Families attending a festival in Palma Campania, near Naples, had packed onto the chair swing ride on Sunday afternoon, July 10, when the accident happened.

Footage shows the base of the ride starting to shake violently shortly after reaching full speed.

Bystanders can be heard shouting as it then begins to lift free from its safety shackles and topples over onto its side.

Parents were then seen rushing over to check on their children.

One 12-year-old remained in hospital on Wednesday, July 13, according to local media.

Detectives are investigating an individual responsible for the fairground on suspicion of causing injury through negligence by allowing the ride to suffer structural failure.

The fairground operator had earlier told local reporters it was a "miracle nobody was killed".

The ride collapsed just a few hours before the fairground was due to end, the town’s mayor said.

Watch the video below.