A student armed with a knife has attacked staff and other students in Oslo, wounding four, police said.

The boy – who studied at the school – was arrested after reports he attacked staff with a knife. The motive was not immediately clear.

Police later confirmed the victims suffered bite marks and had been stabbed with a knife and fork taken from the canteen.

Four employees at Brynseng School in the east of the city were taken to hospital with minor injuries.