It could have been an explosive game of fetch.

When a man in the U.K. saw a round object on the beach while walking his dog recently, he decided to have a little fun. He picked it up, tossed it around, and let his pooch fetch it. But the object was far from a dog toy — instead it was a live grenade likely from WWII that had washed up on shore.

(Source: Shutterstock)

(Source: Shutterstock)

Luckily, the Independent notes, a bomb expert was in the area and saw what was happening. He quickly put a stop to the little game and cordoned off the area and called in authorities. It was later detonated.

According to the Independent, it’s the fifth grenade to be found in the area recently, and authorities believe it could be from the booty of a sunken military ship.

“That crate might be breaking up or has been disturbed by dredging in the port and has resulted in these five devices being washed ashore along the same stretch of beach,” Inspector Paul Butcher told the outlet.

“We are asking people to be vigilant if visiting this beach and to dial 999 if they find any of these devices,” he added. “Some of them have been covered in barnacles but the one yesterday looked almost as new despite being in the sea, possibly for many years.”