An 18-year-old woman who was a passenger in a car died in hospital following a night time collision in Aberystwyth .
Dyfed-Powys Police confirmed the teenager suffered fatal injuries in the crash, which involved a black Vauxhall Astra and a silver Audi A6.
A force spokeswoman said: "Sadly, an 18-year-old sustained fatal injuries and passed away at hospital this morning."
Emergency services were called to the A487 in Comins Coch, Aberystwyth, at around 10pm on Saturday, November 16.
Police said the Astra was travelling out of Aberystwyth, heading towards Bow Street. The teenager was a passenger in the Astra.
Traffic reports showed the A487 was closed from 10pm on Saturday to 7.45am on Sunday.
The road was closed in both directions with the stretch between the A4159 and the B4572 affected.
A spokesman for the Welsh Ambulance Service confirmed four people suffered "serious injuries" and were taken to Bronglais Hospital.
Five ambulances and a rapid response vehicle attended the scene.
He confirmed there was a further call at 2.54am on Sunday requesting "air transport" for a patient from Bronglais Hospital.
He said he could not confirm whether the patient had been involved in the collision.
Penarth Coastguard said they were called to set up the helicopter landing site at Blackweir in Cardiff at 3.50am.
A spokesman said: "While returning from our previous call, we were tasked to set up HLS Blackweir for rescue inbound from Aberystwyth."
He said they received a male casualty with head and back trauma. The man was taken to the University Hospital of Wales in Cardiff.
What to do if you're in a collision or have witnessed one:
Anyone who saw the collision or the vehicles involved, or who has dash cam footage, is asked to contact the serious collision investigation unit.
Information can be reported online , by calling 101 or by email [email protected]
Anyone who is deaf, hard of hearing or speech impaired can text 07811 311 908 with reference: DP-20191116-353