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.

At least 10 people, including the gunman, were killed Tuesday at an adult education center in what Sweden’s prime minister called the country’s worst mass

The authorities said that at least 11 people were killed and that the suspect was believed to be among the dead.