Sweden's worst mass shooting left at least 11 people dead, including the gunman, and at least five seriously wounded at an adult education center west of Stockholm as officials warned that the death toll could rise.

The shooting occurred at a center for adult education in the city of Orebro. The suspect is believed to be among the dead, officials said.

Those are the words of Swedish Prime Minister Ulf Kristersson, following what he described as the worst mass shooting in the country's history, with around 10 people killed. The shooting took place at an adult education centre - located on a campus with other schools - in the central city of Orebro at around 12:30 (11:30 GMT).