BOSTON -- A bag of pot found in the city-owned car of Newton Fire Chief Joseph LaCroix last week belongs to his grandson, Marlborough police said Tuesday.

A group of Newton firefighters found the pot on Thursday when they were cleaning the chief's car.

LaCroix’s grandson, Sean LaCroix, 19, admitted to police that the marijuana was his, the MetroWest Daily News reported.

Marlborough police Capt. Paul Valianti said LaCroix and his wife found the pot in their home and hid it with the intentions of confronting their grandson later. LaCroix told his wife to hide it in her car, but she instead stashed it in his department car, police said.

"I deeply regret this incident, and I apologize for any embarrassment this has caused to the members of the Newton Fire Department, Mayor Cohen, and to the citizens of Newton," LaCroix said in a statement last week.

It is unclear if any charges will be filed.