Police are appealing for witnesses following two separate car crashes on the A27 earlier today.
The first happened near the roundabout at Portfield Way, east of the city centre, where the road was closed to allow an air ambulance to land.
The accident happened at 2.15pm and caused traffic to build up all the way back to the Hampshire border.
Sussex Police believe the driver of a Toyota suffered a medical episode and his car collided with a Peugeot travelling in the opposite direction.
Three other people suffered minor injuries.
Diversions were set up through Oving, and the road reopened at 5.35pm.
Then shortly before 5.30pm today, three vehicles travelling east towards Tangmere collided, blocking the outside lane.
They were a Peugeot, a Nissan X-Trail and a Vauxhall Astra.
No one was trapped, but a woman suffered a shoulder injury and a man sustained a neck injury. None were thought to be serious.
Both incidents led to severe traffic delays in the area.
Police have appealed for anyone who witnessed either collision to phone 101 or email firstname.lastname@example.org