Hundreds of small explosives have been recovered from a waterway by a bomb disposal team.
The railway detonators were found by a person cleaning in the River Nene area close to the Carlsberg brewery off Bridge Street, Northampton, on Sunday.
Police closed the road at 16:00 BST for three-and-a-half hours while the emergency team worked at the scene.
A total of 379 detonators, used as a loud warning signal to train drivers, were collected and taken away from the site, Northamptonshire Police said.