All Swedish schools and pre-schools will have to make plans to keep unauthorised people off their premises, the government said on Wednesday, as the country tries to come to terms with the worst school shooting in its history last week.

Officials in Sweden have vowed to determine why a man killed 10 people, and apparently himself, in an unprecedented attack that's shaken their "society to its core."

The shooting occurred at a center for adult education in the city of Orebro. The suspect is believed to be among the dead, officials said.

Five people have been shot at a school in Sweden as authorities warned the danger was not over while armed officers rushed to the scene. Armed police descended on the Risbergska School, an adult educational institute in the city of Örebro some 200 km (125 miles) west of Stockholm on Tuesday.

Government offices, schools and workplaces fell silent in Sweden at midday on Tuesday in remembrance of the victims of a mass shooting at an adult education centre last week when a gunman killed 10 people before turning his weapon on himself.

The king and queen visited the scene of the tragic event that occurred on Tuesday and Swedish flags were flown at half-mast to honor the victims.

OREBRO, Sweden (AP) — Sweden’s worst mass shooting left at least 11 people dead, including the gunman, and at least five seriously wounded at an adult education center west of Stockholm. The gunman’s motive hadn’t been determined by early Wednesday as the Scandinavian nation — where gun violence at schools is very rare — reeled from an attack.

A minute's silence was observed across Sweden on Tuesday to honour the victims of a deadly shooting at an adult education centre in the city of Örebro. The minute's silence was held in Örebro and several other Swedish cities at 12 pm (1100 GMT).