Two Staffordshire bull terriers attacked another dog in the centre of Brighton yesterday (Monday 3 February).
The Staffies were not on a lead when they attacked the other pet in North Street at about 1pm.
The two dogs were seized by police and are currently being looked after.
A homeless 39-year-old man was spoken to at the scene and was arrested on suspicion of a public order offence and assaulting a police officer.
Sussex Police said: “He is currently in custody being questioned.”
Sergeant Dave Bennett said: “No one was seriously injured in the incident but a lot of people were in the area and would have seen it happen.
“I’d like to speak to as many as possible so we can work out exactly what happened.”