A man has been arrested on suspicion of murder after an "altercation" between two dog walkers in a village, police have said.
A 72-year-old man, named locally as Ralph Baxter, was assaulted in Hyde Road in Roade, Northamptonshire, at about 16:20 BST on Wednesday.
Northamptonshire Police said he was treated by paramedics but died a short time later.
A 27-year-old man from Northampton remains in custody.
Mr Baxter had been walking his small dog when there was a clash between his pet and a larger, husky-type dog, said residents.
They also reported that Mr Baxter, a retired civil servant, died at his home close to the scene.
Det Insp Pete Long said he was particularly keen to speak to anyone "who may have witnessed an altercation between two dog walkers in the area".
He appealed for anyone who was in the Hyde Road/Blisworth Road area between 15:50 and 16:20 to contact the force.
"At the present time, and in order to preserve best evidence, we are treating this incident as a murder investigation," he said.
Chief Constable Nick Adderley said the incident was not being treated as coronavirus-related.