Armed police were called to the A259 Brighton Road, Newhaven, at its junction with Murray Road after a report of a potential firearms incident at 5.10pm on Sunday (December 30).
The road was closed for some 20 minutes while the circumstances were investigated.
It was quickly established that the call had resulted from an altercation between a group of boys and a man claimed to have said he had a gun.
Having found no credible risk and with no one harmed, officers stood down and the road was re-opened at 6pm.
Sergeant Stuart Mullins said: “Thanks are due to motorists whose journeys were disrupted but who showed great patience while the incident was dealt with. People’s safety is always our first consideration in such circumstances.”