A 12-year-old boy suspected of shooting and killing a classmate and wounding two girls of the same age at a school in Finland said he had been motivated by bullying, police have said, as flags flew at half-mast across the country, Ednews reports via The Guardian.

Finland was in mourning after the 12-year-old was alleged to have arrived at Viertola school in Vantaa, a city north of the capital, Helsinki, armed with a handgun on Tuesday morning.

State agencies and institutions were ordered to lower their flags to honour the victims and members of parliament paid their respects. Outside the school, a sea of candles and flowers had been left in the snow.

The suspect told police during questioning that he had been bullied, Eastern Uusimaa police said, adding that this confirmed the findings of their preliminary investigation. The suspect had moved to the school at the start of the year.

Police said that after the shooting, the suspect went on to threaten students who were on their way to school in Siltamäki, Helsinki, with a gun.

“Since the Viertola shooting, the police have become aware of an exceptionally large number of different threats, all of which are thoroughly investigated by the police and taken very seriously,” the police said in a statement.

The revolver-style handgun used in the shooting belonged to a close relative, police said, in relation to which a separate firearms offence was being investigated.

As a result of the suspect’s age, he is not deemed to be criminally responsible under Finnish law, which means he cannot be arrested or detained. After police questioning and pre-trial investigation measures, police said the child was handed over to social welfare authorities.

Police said the person killed in Tuesday’s shooting was male and a Finnish citizen and that the two who were seriously injured, and remain hospitalised, were female. One of the hospitalised victims is a dual citizen of Finland and Kosovo and the other is a Finnish citizen.

They warned of misinformation circulating on social media about the shooting, including screenshots of social media profiles belonging to people unrelated to the case.

“We want to emphasise that such activities are illegal and may cause harm to completely innocent people,” said police. “This behaviour also activates others, who deliberately spread false information, and boosts online trolling.”

City authorities praised the school’s response to the shooting, saying that if the city had not been so well prepared, the outcome could have been “significantly worse”.