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."

Sweden’s prime minister said the attack at the Risbergska School was the worst mass shooting in country’s history

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.

One day after the killings at an adult educational center, some gathered to lay flowers and come to grips with the violence.

Sweden's right-wing government said on Friday it would seek to tighten gun laws in the wake of the country's deadliest mass shooting at an adult education centre where the attacker appeared to have used several of his own licensed rifles.

Gunman kills 11 at a Swedish adult education center in Örebro. Investigators say he acted alone. #Sweden #Örebro #MassShooting #GunViolence

The gunman was among the 11 people killed in the worst shooting in the history of Sweden at an adult education centre west of Stockholm. On Tuesday, police received reports of a shooting in Orebro, a city 200km (124 miles) west of Stockholm, at 12.33pm local time and engaged in an exchange of bullets with the suspect.

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).