Police are appealing for witnesses to a collision on the A27 at Wilmington, at 4.47pm on Thursday (November 28).
Two people were slightly injured and the incident caused significant delays.
The collision, 21 metres west of a junction with Pound Lane, involved a white Vauxhall Combo van and a black Peugeot 207 travelling in the same direction.
A third vehicle may also have been struck but is thought to have driven off before the arrival of police.
A 66-year-old man driving the Peugeot and his passenger, a 60-year-old man, were both taken to the Eastbourne District General Hospital with slight injuries. The passenger was released but the driver was detained overnight for observation.
An 18-year-old man driving the Vauxhall and his passenger, a man aged 23, both escaped injury.
Anyone who saw what happened, and the driver of the third vehicle thought to have been involved, is asked to phone Sussex Police on 101, quoting serial 1131 of 28/11, or e-mail: firstname.lastname@example.org