Bomb disposal experts have been called to a country lane just outside of Northampton after an amateur metal detectorist discovered a World War II hand grenade.
Precision engineer Tim Whiting, from Brixworth, was dangling a magnet into the river along Merry Tom Lane between Chapel Brampton and Brixworth last night.
The amateur metal detecting enthusiast was hoping to unearth some old coins or unusual artefacts.
But he then pulled out "what looked like a World War II hand grenade", from the water.
"I was pretty surprised," added the 33-year-old who gingerly took the item off the line before taking photos of it and posting the snaps on an internet forum.
After fellow amateur historians confirmed the find, Mr Whiting called 999.
Police have been at the scene overnight and bomb disposal experts have arrived at the lane this morning where it is undestood they will cary out a controlled explosion.
Mr Whiting said it was sheer luck that no one had stepped on the relic before.
"I used to swim in there as a child," he said.