Dental records are being used to determine the identities of two people who died in Friday's fiery crash on the M1 Princes Motorway at West Wollongong.
Details of the crash's tragic aftermath emerged as police charged a Sydney man for allegedly causing the horrific, six-vehicle pile-up.
Police said a 65-year-old man was driving a silver Ford Territory south on the M1, when it collided with a truck and dog trailer combination underneath the Mount Keira Road overpass about 2.10pm.
Police allege the man - from Lansdowne in Sydney's southwest - cut off the truck as he changed lanes near the Figtree exit, triggering a deadly chain of events.
It is understood the truck driver, a 42-year-old Albion Park woman, braked to avoid a collision and a Mitsubishi Pajero slammed into the back of the truck.
The Pajero was then hit from behind by an Isuzu rigid truck; the impact so great both vehicles caught fire.
The occupants of the car, believed to be a man and a woman, were trapped inside and died at the scene.
Chief Inspector Phil Brooks, from the NSW Police Traffic and Highway Patrol Command, said investigators were working to formally determine their identities and that process "will take some time".
"We'll certainly be going through a range of forensic and coronial procedures in the hope that we can identify these people," Insp Brooks said.
"We're certainly following a number of leads but, given the circumstances of how the event unfolded, we will have to rely on dental and other records to positively identify the two parties involved."
The driver of the Isuzu truck, a 47-year-old Cordeaux Heights man, was able to free himself from the cabin before the fire took hold. He wasn't injured.
A Honda Odyssey, driven by a 30-year-old man from Auburn, and a Toyota Prado, with a 51-year-old Orange woman behind the wheel, were also caught up in the crash. All five surviving drivers were taken to hospital for mandatory testing.
Nine people were assessed by paramedics at the scene; none of whom required hospitalisation.
The Territory driver was charged with two counts of dangerous driving causing death, as well as negligent driving causing death.
"We'll be alleging the actions of the accused driver in this matter, in changing lanes into the path of the truck and dog trailer, has caused a chain of events," Insp Brooks said.
The man was given conditional police bail and is due to front Wollongong Local Court on July 23.
Investigations into the crash are ongoing. Anyone with dashcam or mobile phone footage from the scene should contact police.
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