After questioning the students, the guards discovered that 10 of them had entered the border zone, with five suspected of having illegally crossed the national border from Finland into Russia and back.
The students reportedly filmed themselves circling a red and green pole which marks the Russian border post.
The Southeast Finland Border Guard has launched a pre-trial investigation into the incident. As the age of criminal responsibility in Finland is 15, only students aged 15 and older may face legal consequences, the Border Guard said, according to Ilta-Sanomat.
“The matter is being processed by the border guard,” the school’s principal said. He said that the trip was planned in advance, but declined to provide further comment on the incident.