Three persons are believed to have been killed when a hijacked truck rammed into shoppers in Stockholm, Sweden on Friday.

Police said the vehicle crashed into a group of people on the street outside a shopping centre.

Shots were heard being fired and the driver, who was wearing a balaclava, is said to have escaped, according to witnesses.

A Swedish radio reporter said she had seen at least five dead bodies, but official reports put the number of dead at three.

The truck is understood to have been stolen or hijacked from a Spendrups brewery.

The incident took place at Ahlens Mall in Klarabergsgatan.

Prime Minister Stefan Löfven immediately confirmed that the incident was a terror attack and one person has been arrested.