Mourners gathered outside a southern Finland school Wednesday, a day after a 12-year-old student was accused of fatally shooting a boy and seriously wounding two girls all the same age with a handgun. The suspect, a sixth grader who attended the school, was apprehended less than an hour later.

The attack shocked the Nordic nation, where Finnish blue-and-white flags were hoisted at half-staff and scores of people including parents, teachers and fellow students laid flowers and lit candles in the snowy landscape near the school building where the shooting occurred.

The Finnish government declared Wednesday a nationwide day of mourning, ordering all state agencies and institutions to lower the national flag to half-staff. Many private households across Finland joined in the commemoration.

FINLAND SCHOOL SHOOTING LEAVES MULTIPLE WOUNDED, SUSPECT ARRESTED

Police said one of the wounded girls has a dual Finland-Kosovo citizenship. The shooter and the victims were all classmates.

Mourners outside Finnish school

An assortment of candles, flowers and other memorabilia were placed outside the Viertola school in Finland, one day after a 12-year-old student was suspected of opening fire at his classmates — killing one and seriously wounding two other students. (Jussi Nukari/Lehtikuva via AP)

In a statement on Wednesday, police said they have established a preliminary motive for the killing, which was carried out with "a revolver-like handgun," but said the investigation was ongoing. Finnish public broadcaster YLE said the suspect had allegedly been bullied at school.

On Tuesday, heavily armed police cordoned off the Viertola school, an 800-student secondary school in the city of Vantaa, just outside Helsinki.

Police said the deceased boy died instantly after being shot. The suspect was detained in the Helsinki area less than an hour after the shooting, with a handgun in his possession. The gun was licensed to a relative of the suspect who was not immediately identified. Police said he admitted to the shooting in an initial police hearing.

The minimum age of criminal liability in Finland is 15 years, which means the suspect cannot be formally arrested. A suspect younger than 15 can only be questioned by the police before they are handed over to child welfare authorities.

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Finland has witnessed two major deadly school shootings in 2007 and 2008. In their wake, the country tightened its gun laws, raising the minimum age for firearms ownership and giving police greater powers to perform background checks on individuals applying for a gun license.

The nation of 5.6 million has more than 1.5 million licensed firearms, and about 430,000 license holders, according to the Finnish Interior Ministry. Hunting and gun-ownership are deeply rooted traditions in this sparsely-populated northern European country, where target practice is also a widespread hobby.