Witnesses are being sought after a 35 year old woman from Bexhill died and a 37 year old man from St Leonards suffered life threatening injuries after their car left the road near Pevensey.
Police say it happened at around 7.30pm at the point where Hankham Hall Road crosses the A27 at around 7.30pm yesterday (Friday).
Anyone with information is being asked to come forward.
Sergeant Richard Hobbs from the Surrey and Sussex Roads Policing Unit said:
"This is a tragic incident and we are seeking witnesses as to what happened.
"Anyone who saw the white Ford Fiesta being driven from the Stone Cross roundabout towards the Wallsend roundabout moments before the collision at around 7.30pm or who may have captured dash cam footage is urged to email [email protected] or call 101 quoting Operation Stark."
The road, which was closed while rescue, recovery and collision investigation work was carried out, was re-opened around 5.15am.