About 50 youngsters gathered to fight in a school compound in Lieto, South Western part of the country.
The youngsters, between the age of 15 and 18 from Lieto and the neighbouring municipality of Aura, were armed with baseball bats.
According to South Western police, two youngsters were injured and rushed to hospital but the extent of their injuries was not immediately known.
Police have detained one and are currently investigating assault charges.
Police detective Kirsi Alaspää suspected that the youngsters arranged the gathering using social media platforms on the internet.
