Sign up for the Morning Brief email newsletter to get weekday updates from The Weather Channel and our meteorologists.

An unsuspecting fisherman pulled a military-grade explosive from a Massachusetts river. Police say the man was using magnets to search for items made of metal hidden at the bottom of the Charles River, in the town of Needham.

The man notified authorities immediately, and local police, firefighters and the Massachusetts State Bomb Squad arrived on scene. The fisherman, identified as Sean Martell, had placed the explosive on a sidewalk near the bridge where he was fishing.

Weather in your inbox

Forecast Location

Sign Up

By signing up you agree to the Terms & Privacy Policy. Unsubscribe at any time.

(MORE: Watch A WWII Bomb Explode)

Members of the bomb squad quickly determined that the object was a military projectile in a severely deteriorated state and needed to be disposed of safely. Police said the rusty cylinder, which measured 12 inches long and about 4 inches wide, appears to have been an unexploded artillery shell.

Officials say the explosive was secured and transported to a disposal site on the edge of town, where it was rendered safe without incident. However, police warned residents they could hear an explosion.

It’s fairly uncommon for a live round to be discovered by a magnet fisherman. According to police, old artillery equipment is usually found washed up on beaches or dug up by construction crews.

(MORE: WWII-Era Bomb Washes Up On California Beach)

Martell, known on YouTube as Brockton Magnet Fisher, was streaming live on his channel when he pulled the mortar from the river. He announced plans to post the full video of the discovery Monday.

For more crazy catches on weather.com, click here.

The Weather Company’s primary journalistic mission is to report on breaking weather news, the environment and the importance of science to our lives.