Solveig Eid, the headmistress of Risil School in Vestby, said the janitor arrived for work and discovered the door to a classroom had been smashed in, The Local.no reported Tuesday.
"Our janitor he came to school and he saw a broken door," Eid said."He thought that some children or teenagers had been having a party or whatever and had broken the glass."
Eid said the janitor checked security camera footage and identified the culprits.
"Suddenly he saw a mother moose and two calves... and they were very much afraid," Eid said.
Eid said the mother seemed to have been frightened by her own reflection.
"The mother of the calves, she saw herself in the glass and she wasn't happy about that. She wanted to protect her kids," she said.
"We had a big problem explaining to the children what a moose is and what a calf is. But we showed them the video and they laughed," Eid said.