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 shooting. But a final death toll, a conclusive number of wounded and a motive hadn’t yet been determined hours later.