One of the dead was social-democrat council leader Tiina Wilen-Jappinen as confirmed by the town mayor Pertti Lintunen. Ms. Wilen-Jappinen was in her 50s.
Also killed were two local journalists who are as yet not being named.
The 23-year-old suspect was quickly arrested--he was armed with a shotgun and had a record of violent crimes the local police said. He was interrogated on Sunday but the motive for the shootings remains unclear, but it appears the attacker may have chosen his victims at random, investigators said.
No additional suspects are being sought.
Finland's crime rate is relatively low compared to other European nations. Hunting is quite popular and thus it has one of the biggest gun ownerships per capita in the world.
It will obviously be a matter of minutes before anti-gun advocates will blame the weapon rather than the killer who used it instead of another method of murder.
According to Imatra authorities, psychological support is being offered to town residents if the need arises.