About 10 people including the gunman have been killed at an adult education center in what Sweden’s prime minister called the country’s “worst mass shooting.”

Swedish police confirm around 10 people were killed at a school for adults on the outskirts of Stockholm. The gunman is believed to be among the dead.

Police said about 10 people had died during a shooting Tuesday at an adult education center in the city of Örebro, and the final death toll may change, as damage at the crime scene was so extensive that investigators were unable to be more definitive.