Emergency services were called to the incident on the A272 around 11.30am on Monday (March 28).
The collision involved a silver Ford Fiesta, a white Ford Fiesta, and a Skania tipper truck.
Sadly two people were pronounced dead at the scene – an 83-year-old man from Worthing, and a 30-year-old woman from Aylesford, Kent.
Two other women, both aged 23 and from Kent, were taken to hospital with serious injuries.
Road closures remained in place while police, the fire service, ambulance service and air ambulance service responded to the incident.
Detective Sergeant Rob Baldwin, of the Surrey & Sussex Serious Collision Investigation Unit, said: “We would particularly like to speak with anyone travelling on the A272 between Cowfold village and Littleworth Lane to the west, on Monday morning between 11.15am and 11.30am, who has dash camera footage. We’d also like to speak with any resident or business who has CCTV footage showing the road between those locations.”
Information can be reported by email to [email protected] or by calling 101 and quoting Operation Banwell.