The road has since re-opened after traffic diversions were in place for a time.
Sergeant Fenton said: “Officers attended, along with colleagues from the Northern Ireland Ambulance Service and the Northern Ireland Fire & Rescue Service.
“Three people were taken to hospital for treatment to their injuries. One man remains in a serious condition in hospital.
“We are appealing to anyone who was in the area at the time and witnessed this collision, or who may have dash-cam footage, to contact police on 101 quoting reference 2143 of 13/05/22.
“Alternatively, you can submit a report online using our non-emergency reporting form via http://www.psni.police.uk/makeareport/.
“You can also contact Crimestoppers anonymously on 0800 555 111 or online at http://crimestoppers-uk.org/”