Police in Oslo have cordoned off a large section of a busy street after finding what they said was a "bomb-like" device.

The official police Twitter account said a man had been arrested and police chief Vidar Pedersen said bomb disposal experts were on the scene in the Norwegian capital.

Police swept through the area to remove people from bars and restaurants.

"Every restaurant was being closed," said 23-year-old Malin Myrvold, who witnessed the scene from a fourth-storey window.

"You could see cops in heavy armour going in every store and restaurant.

"We were trying to see what was going on. The police were screaming at us to get back inside and stay where we were."

Norway was put on high alert after the lorry attack in neighbouring Sweden on Friday that killed four people and injured 15 in the capital Stockholm.

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

It is unclear whether the arrested suspect, a 39-year-old native of Uzbekistan, was also a Swedish citizen or resident or even how long he had been in the country.