All three victims were 12 years old, according to what the police had previously indicated, and a 12-year-old suspect was in custody.
Parents told the Finnish media that the shooting happened in a Viertola school classroom in Vantaa, which is north of Helsinki, the capital.
At 09:17 (06:17 GMT), according to the police, they reached the school in nine minutes and attended to the three victims.
They also said that one of the kids passed away right away.
As soon as the police came, the suspect fled, and at 10:00, he was apprehended “in a calm manner” in Helsinki’s northern Siltamaki neighborhood.
According to the police, he was in possession of a gun that they had confiscated from him, and during the initial interview, he had acknowledged to firing the gun.
An investigation into murder and attempted murder has already been launched.