CALAIS – The Bureau of Alcohol, Tobacco and Firearms and explosives was inside a local hardware store for a few hours Thursday morning, but no one is saying why.

The mystery played out at Johnson’s True Value Hardware Store on North Street.

Calais police confirmed their department had assisted the agency, but did not elaborate.

Eyewitnesses said Sgt. David Randall of the Calais Police Department was stationed outside the door while federal agents were inside. That was around 9 a.m.

The store was open Thursday afternoon and it was business as usual.

Efforts to contact owner David Johnson were unsuccessful. Even going to the store proved to be unsuccessful. One employee said Johnson was busy talking with two suppliers and a vendor.

Shortly after that, another employee looked up the stairs and said he wasn’t “tied” up at all.

Then a third employee said Johnson was exhausted and had left for the day. That was around 3:30 p.m.

ATF did not return a telephone call to its Boston office on Thursday.

But according to its Web site, the agency “performs the dual responsibilities of enforcing federal criminal laws and regulating the firearms and explosives industries.”

Johnson’s Hardware does sell guns and ammunition at its store.

The store has been at its current location on North Street for the past few years.

In 1996 the store, which originally was located on Main Street, was destroyed after a 14-year-old boy set a fire in an upstairs apartment over the store. The fire destroyed the historic, four-story brick building and threatened other buildings. David Johnson’s father, Rocky, owned the store at that time.