When police went to his house later that day, they discovered improperly secured guns -- a number of rifles, handguns and ammunition.
Millbury police Chief Donald Desorcy said he is certain the teacher knew he was carrying ammunition when he walked into school Thursday, even though the man claimed it was an accident.
"He explained to us that he had been out shooting the day before and apparently had these rounds, these magazines in his clothing, and apparently he wore the same clothing to school yesterday," Desorcy said.
The teacher was licensed to carry and his weapons were registered, but his license has now been revoked under the police chief's discretion.
"To me that’s just not sound judgement, an individual not thinking clearly or have a strong concept of gun ownership or gun responsibility," Desorcy said.
Police said they aren't identifying the man because he has not been criminally charged. He has, however, been fired from the district.