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.

The suspected gunman in a deadly school shooting in Sweden shot himself after killing 10 people on Tuesday, police believe. Armed police exchanged fire with an unnamed shooter at Risbergska School in Örebro, 125 miles west of Stockholm, in what Swedish prime minister Ulf Kristersson has described as the worst mass shooting in the country’s history.