Police are continuing to investigate a collision on the A487 in Ceredigion, which seriously injured four people.
The incident, involving two vehicles and a caravan, happened between Llanrhystud and Aberystwyth, and caused the road to be closed for seven hours.
Two of the injured were flown by helicopter to Bronglais Hospital and were said to be seriously ill.
Two others, said to be in a less serious condition, were taken to hospital in Carmarthen.
The incident happened at around 1400 BST on Tuesday and police were still at the scene at 2100 BST.
Officers are appealing for witnesses to contact them at Aberystwyth police station by dialling 101.
The two cars involved were a Mitsubishi L200 from the Llanelli area and a Corsa from the Aberystwyth area.
The driver and passenger of the Corsa are both in a critical condition in hospital.
The driver is a 20-year-old man from Aberystwyth, and is currently at Bronglais Hospital in Aberystwyth.
The passenger is a 20-year-old woman, also from the Aberystwyth area, who being looked after at The Heath Hospital in Cardiff.
The cause of the accident is still under investigation.