Swedish authorities have confirmed 11 people died in Tuesday's atrocity, including the gunman, after the suspect prowled through the halls of the adult education centre, picking off victims

The police responding to the attack encountered firing so intense that they struggled to tell how many gunmen were on the scene, an official said.

The suspect, named in reports as 35-year-old local man Rickard Andersson, was reported to be a former student of the school in Orebo, a city 157 km (98 miles) west of Stockholm, where the attack took place on Tuesday. Eleven people died in the shooting, including the attacker, with at least six others injured.