Firearms officers were called in after a gun was discovered by members of the public in a canal in Watford.

There was "utter shock" when the weapon was pulled out of the Grand Union Canal on January 9 - but police have since confirmed it was a BB gun.

Magnet fishing is a growing hobby that involves sending a powerful magnet into the water that is capable of lifting a tonne.

The fishers are used to finding valuable scrap metal and other appliances so they were understandably taken aback when what they thought could be a live firearm emerged from the water.

Watford Observer: The weapon found by magnet fishers in the Grand Union Canal. Credit: The Narrowboat that James built/YouTubeThe weapon found by magnet fishers in the Grand Union Canal. Credit: The Narrowboat that James built/YouTube

James Posner, who lives on a narrowboat on the canal, said: "I was out with London Magnet Fishing and the Middlesex Magneteers and they were fishing along a ten metre stretch between Cassiobury Park and Croxley.

"In that ten metres, we pulled out microwaves, a laptop, and vast amounts of lead and chimneys.

"But there was utter shock when the gun was pulled out. It looked like it had a loaded chamber and a safety catch and when the police officer arrived, they said it could be a live gun and it was called in.

"To me, it didn't look like it had been in the water long, perhaps less than a year."

Watch a YouTube video by Mr Posner of the discovery here.

Watford Observer: A police officer first on scene inspecting the discovery. Credit: The Narrowboat that James built/YouTubeA police officer first on scene inspecting the discovery. Credit: The Narrowboat that James built/YouTube

Firearms officers arrived to take the gun away but following inspections, Hertfordshire Constabulary has said the weapon was a BB gun.

A police spokesperson said: "We were called to reports of a handgun found in the river under the bridge in Rousebarn Lane on Sunday January 9.

"Officers attended the scene and the item, suspected to be a BB gun, was seized by police.

"We can confirm it was a BB gun and officers have carried out checks to see if there were any recent incidents whereby a gun/imitation was used.

"None have been identified and the item is now likely to be destroyed."