Emergency services were reportedly called to Ellangowan Road, Ellangowan, about 8.50pm Saturday, where they found a sedan had left the road, hit a tree and caught fire.
Passers-by tried to help but the 18-year-old man driving the sedan had already died and the only passenger, an 18-year-old woman, also soon died on-scene.
Richmond Police District officers on Sunday said they were investigating circumstances surrounding the crash and would prepare a report for the Coroner.
Anyone with information about this incident is urged to contact Crime Stoppers: 1800 333 000 or https://nsw.crimestoppers.com.