Eleven people were killed in a shooting at the Risbergska School in Örebro, some 125 miles west of Stockholm, on Tuesday.Police said the gunman was believed to be among those killed and a search for other possible victims was continuing at the school.

School attacks are relatively rare in Sweden, but the country has suffered shootings and bombings linked to gang violence that kill dozens of people each year.

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.”