A man has been arrested in connection with the Stockholm lorry attack, with reports suggesting he was detained in Marsta, around 25 miles north of the Swedish capital.

Swedish media are reporting that he admitted being involved in the attack and was captured wearing a balaclava, but officers do not believe he was the driver of the truck.

He is reported to be a 39-year-old Uzbek national whose registered address is in suburban Stockholm. The man is said to work in the building industry and have four children, but acquaintances said he had never discussed politics or religion with them.

Some reports suggested he had previously posted pro-Isis propaganda on his Facebook page. But friends told Swedish newspaper Aftonbladet they did not believe he had anything to do with the attack.

At least four people are confirmed to have have been killed and 15 are being treated in hospital after a truck was driven into crowds in the centre of the city on Friday afternoon.

In pictures: Stockholm truck attack Show all 15 1 /15 In pictures: Stockholm truck attack In pictures: Stockholm truck attack 3 people dead when a truck crashed into Ahlens department store in central Stockholm, Sweden Rex In pictures: Stockholm truck attack People were killed when a truck crashed into department store Ahlens on Drottninggatan, in central Stockholm Reuters In pictures: Stockholm truck attack Special Police forces work at the scene where a truck crashed into the Ahlens department store at Drottninggatan in central Stockholm Getty Images In pictures: Stockholm truck attack Woman is assisted at the scene after a truck crashed into an Ahlens department store in Stockholm Rex In pictures: Stockholm truck attack A policewoman in a gas mask operates at the scene where a truck crashed into the Ahlens department store at Drottninggatan in central Stockholm Getty Images In pictures: Stockholm truck attack People react at the scene where a truck crashed into the Ahlens department store at Drottninggatan in central Stockholm Rex In pictures: Stockholm truck attack Reports say three people have died after a truck crashed into an Ahlens department store in Stockholm Rex In pictures: Stockholm truck attack Armed police operates at the scene where a truck crashed into the Ahlens department store at Drottninggatan in central Stockholm Getty Images In pictures: Stockholm truck attack People react at the scene where a truck crashed into the Ahlens department store at Drottninggatan in central Stockholm Getty Images In pictures: Stockholm truck attack Emergency services close to the scene of an incident in Drottninggatan, a street in the centre of Stockholm, Sweden Lasse Gare/PA Wire In pictures: Stockholm truck attack Passers react at the scene where a truck crashed into the Ahlens department store at Drottninggatan in central Stockholm Getty Images In pictures: Stockholm truck attack People killed in incident when a truck was driven into a department store in central Stockholm Reuters In pictures: Stockholm truck attack Police officers work at the scene where a truck crashed into the Ahlens department store at Drottninggatan in central Stockholm Getty Images In pictures: Stockholm truck attack A general view shows a Ahlens department store after a truck reportedly crashed into it, at Drottninggatan in central Stockholm, Sweden EPA In pictures: Stockholm truck attack A view of a street after a truck reportedly crashed into a department store in central Stockholm, Sweden EPA

Police released an image of a man wearing a green jacket, grey hoodie and white shoes who they are hunting in connection with the attack, but stopped short of formally describing him as a suspect.

Jan Evensson of Stockholm police said the man arrested in Märsta "matched exactly" the profile of the person in the image.