POLICE are investigating a head-on crash which seriously injured two people and closed a Central Coast highway for several hours on Sunday.
Emergency services responded to reports a ute and sedan had collided on the Old Pacific Highway at Mount White just after 7am on October 27.
The 27-year-old man driving the sedan was trapped for about an hour until rescue specialists managed to free him.
He was airlifted by the Westpac Rescue Helicopter to the Royal North Shore Hospital in a serious but stable condition, according to NSW Police.
The 45-year-old man behind the wheel of the ute was taken to Gosford Police Station, but has since been released pending further investigation.
One passenger in the ute - a 19-year-old woman - was also flown to hospital in a serious but stable condition, police said.
Two other passengers in the ute - a second 19-year-old woman and a woman aged in her 40s - suffered minor injuries.
Brisbane Waters police established a crime scene and specialist officers from the Crash Investigation Unit were at the scene on Sunday working to piece together how the incident unfolded.
The Old Pacific Highway remained closed in both directions at about 1pm police have warned drivers to expect significant delays while officers comb the crime scene.
Motorists should avoid the area.
Divert via the M1 Pacific Motorway, which is suitable for all vehicles.
Police have urged anyone with information, dashcam or mobile phone footage in relation to the crash to contact Gosford police or Crime Stoppers on 1800 333 000.
Investigations continue.