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.

Survivors of Sweden's worst mass shooting on Wednesday recalled trying to save the lives of their comrades at a school for adults in Örebro, a day after a gunman killed 11 people on what the prime minister called a "dark day" in the country's history.

A gunman opened fire at an adult education center in the Swedish city of Örebro on Tuesday, killing at least 10 people in what the country’s prime minister called the “worst mass shooting in Swedish history.