Despite floods and early closure of the school on Thursday, thieves broke into the Monkey Town Government Primary School in Lower Barrackpore.
It is not certain whether or not any item was stolen.
However, despite the burglary, the school continued to hold its Christmas concert and end of term party for the children.
The principal told police that she secured the school around midday on Thursday and dismissed because of floods at Lower Barrackpore.
The school is situated on a hill near a river.
Police said sometime during Thursday night, someone prised open the door at the office. The area was dusted for fingerprints.
No arrests have yet been made but Barrackpore police are continuing investigations.