An angry moose, probably upset by its own reflection, smashed through the glass doors of a Norwegian school at the weekend.

When students at the Risil secondary school in Vestby, southeast of Oslo, found broken glass on Monday morning, security cameras showed the perpetrator was not a delinquent teenager.

"The janitor looked through the surveillance tape, hoping to identify the thug who did this, but was shocked when he saw that the damage was done by a moose and her two calves," school principal Solveig Eid told Reuters.

Eid believes the moose must have seen her own reflection in the glass door and charged towards it. A Norwegian moose can be as tall as two metres (6 ft) and weigh as much as 400 kg.