A bomb squad was deployed after an eight-year-old boy found a hand grenade while fishing with his mum.
Tyler Bell discovered the device while magnet fishing in the River Douglas in Shevington, Wigan.
After his mum, Charlotte called 999 police arrived and taped off Gathurst Lane, between Princes Park and Ackhurst Lane.
Bomb disposal officers were summoned to assess the grenade.
Ms Ball said: “We weren’t 100% sure what it was at first, which is why I picked it up.
“I saw the ridges and knew what it was. I was shocked.
“We rang the police and they came and called the bomb squad. They have sectioned off the road.
“There are two police vans and two police cars.”
Ms Ball took Tyler and his brother Liam, 12, fishing to pass time during lockdown.
She said: “You don’t expect to come across something like that.
“It was the first time we’ve been and it was just something to pass the time during lockdown and keep the kids entertained.”
Ms Bell said that her son wasn’t scared, but excited by his discovery.
“He is so excited,” she said. “He can’t wait to tell his friends he has found a grenade.”
A spokesperson for Greater Manchester Police said: “Police were called at around 11.30am on Monday 18 January to a report of a possible historic unexploded device being found in the canal off Gathurst Lane in the Shevington area of Wigan.
“Officers are in attendance and road closures are in place.
“EOD are on their way to the scene to carry out an assessment of the item.”
Police left the scene shortly before 4pm.