This is the dramatic moment a bystander tackled a suspected teenage thief inside a supermarket in Florida.

Bodycam footage shows officers chasing the 15-year-old suspect through a store in Port St Lucie on September 1.

A quick-thinking shopper stepped in to help, taking down the masked teen as he ran past, allowing police to bring the pursuit to a swift end.

Authorities said the incident began at a Mattress Firm store, where the suspect was seen discarding an empty jewellery box.

Sensing something was wrong, the store manager alerted staff at the nearby Burlington store.

Employees there confirmed that a theft had just occurred and identified the suspect as the same individual who had fled with the item.

While police were responding, officers spotted the suspect sitting on a park bench in the area.

The thief, still wearing a balaclava, bolted as soon as officers approached. Witnesses pointed police toward Publix, where the chase continued.

Master Sergeant Dominick Mesiti acknowledged the bystander's actions while also cautioning the public about the potential risks of intervening during police pursuits.

He added: 'If it were a more serious crime and if a suspect could've been armed, they may have used a weapon on that Good Samaritan. So again, very thankful that this gentleman stepped up, but they have to keep in mind that they're putting themselves in danger.'