Four people are dead after two large utes collided head on on the Barton Highway north of Canberra on Friday morning.
The crash happened about 6:45am in heavy rain near Casuarina Lane, between the ACT village of Hall and the New South Wales town of Murrumbateman.
Warning: This story contains images that may be confronting.
The 52-year-old female driver and 54-year-old male passenger of a Mitsubishi Triton ute died at the scene.
The male driver and a male passenger of a Ford Ranger ute also died. They have not been formally identified, but police believe they were aged in their 20s.
Another male passenger in the Ford was treated at the scene and taken to Canberra Hospital. He is in a critical condition.
Emergency crews from the ACT and NSW, including three rescue helicopters, arrived shortly after the collision.
Police officers established a crime scene and were investigating the circumstances that led to the crash.
A NSW Police spokeswoman asked anyone with dashcam footage or other information to contact Crime Stoppers on 1800 333 000.
The Barton Highway was closed for about seven hours after the fatal collision, as investigators assessed the site.
Motorists in the busy holiday traffic were forced to take lengthy detours via the Federal Highway.
However, the Barton Highway reopened in the middle of Friday afternoon.
Six NSW road deaths within a day
The four deaths took NSW's Easter long weekend road toll to six, following two other fatal crashes on Thursday night.
NSW Police's Acting Assistant Commissioner Tracy Chapman said a large number of officers were deployed across the state to monitor the holiday traffic.
She described the Barton Highway incident as traumatic for everyone, including the police who responded to it.
"Ultimately, our thoughts are with the family, the friends and the local community that will no doubt feel the impact of these deaths," she said.
Assistant Commission Chapman said it was too early to speculate on the causes of the collision but urged all drivers "to follow the rules".
"The message is pretty simple: drive to the speed limit, drive to the conditions, don't drive while under the influence of drugs and alcohol … and focus on the road not your phones," she said.
"And that's the message we need motorists to heed to ensure that we have an incident-free weekend."
Deadly highway slowly being upgraded
Locals have long complained about the Barton Highway's quality.
The rural highway has a 100kph speed limit and is one of only three major roads connecting Canberra with NSW.
However, it has just two lanes for most of its 52-kilometre length.
Four years ago, a NSW government report noted that the highway's casualty crash rate was about 50 per cent higher than similarly classified roads.
The federal and NSW governments have committed to widening the road into a four-lane highway.
However, this project has only just begun and is expected to take many years.
