A fight broke out in the street between two drivers last night.
Police say one motorist verbally abused a man in another car while driving past him just before 7.20pm, in Brownlow Road, Borehamwood.
He then got out of his car, where he is believed to have assaulted the other man.
The second man suffered cuts to his face as a result. A witness reported seeing a man with a bloody nose just after 7.30pm.
A 47-year-old man from Borehamwood has been arrested on suspicion of assault occasioning actual bodily harm, but has been released on police bail while investigations continue.