HELSINKI — Flags have been flying at half-mast across Finland after a child was killed and two others seriously wounded in a shooting at a school on Tuesday.

The shooting took place in a classroom at Viertola school in Vantaa, to the north of the capital, Helsinki.

Police said all three victims were 12 and that a suspect, also aged 12, had fled after the shooting but was later detained.

One of the injured children is Kosovan, its foreign ministry said.

All public buildings lowered their flags from 8:00 (05:00 GMT) on Wednesday to mark a day of mourning, the interior ministry said.

According to the Finnish TV channel MTV Uutiset, the boy wore a mask and noise-cancelling headphones while carrying out the shooting.

He ran off as soon as police arrived and was eventually detained "in a calm manner" in the northern Siltamaki district of Helsinki.

Police have opened an investigation into murder and attempted murder.

There has been no official update on the condition of the injured children.

In a statement on Wednesday, police said they are looking into a possible motive but will not yet be releasing details to the public yet.

"There is a lot of different, and partly incorrect, information about what happened in the different channels of social media. The police still want to remind you that spreading incorrect information on social media is a crime," it said.

Children under the age of 15 are not criminally liable in Finland, so the suspect has not been remanded in custody and will be placed in the care of social services after further questioning.

The suspect is understood to have used a gun licensed to a close relative. Gun ownership is widespread in Finland and children over 15 can have licences to use other people's firearms.

Elina Pekkarinen, Finland's Children's Rights Ombudsman, told Finnish news agency STT, that "for years (we have been repeating) that we need to take violence between children in society seriously".

Acts of violence, particularly amongst children under 15 years old, have been on the rise for several years, she added.

Finland is widely known as a country of hunters and gun enthusiasts and has 430,000 licensed gun owners in a population of 5.6 million, according to government statistics. There is no limit to the number of guns that can be owned and the interior ministry says more than 1.5 million are in circulation. — BBC