Police would like to speak to anyone who may have witnessed an altercation between two motorists on the A27 at Lewes.
The incident, involving a silver or grey Ford Transit and a white Ford Transit Connect, is reported to have taken place at about 4pm on Tuesday (July 11) at Kingston Roundabout, said Sussex Police.
A 33-year-old man from Bexhill, arrested on suspicion of possession of a knife in a public place and driving without due care and attention, has been questioned by police and has been released under investigation, police added.
Anyone who saw what happened is asked to report it online at www.sussex.police.uk/contact-us/response-to-appeal/ quoting serial 1015 of 11/07.
Alternatively, you can visit the Crimestoppers website at www.crimestoppers-uk.org/ or contact the independent charity anonymously on 0800 555 111.