Members of the public rushed to help after a Ford Ranger collided with a Toyota HiAce on the Stuart Highway 75km east of Darwin around 12.50pm on Wednesday.
But the intense fire engulfing the vehicles prevented would-be rescuers from approaching.
Their bravery was on Thursday highlighted by Northern Territory Police who said they did everything they could to save lives.
"Unfortunately, despite the efforts of everyone involved ... five lives were lost," Acting Commander Richard Griffiths said.
Preliminary investigations indicated the Ford Ranger "for unknown reasons" veered onto the wrong side of the road while heading north, crashing into the Toyota, he said.
Police earlier said witnesses had told investigators the Ranger was travelling "at excessive speed" and overtaking dangerously in the minutes leading up to the collision.
Initially police said "at least four lives" had been lost in the crash but on Thursday confirmed five fatalities after careful examination of charred remains in the burnt-out vehicles.
The driver and three occupants in the Ranger died in the crash - two men and two women aged from 23 to 36.
The sole occupant of the Toyota - a 69-year-old woman - also died.
The NT Disaster Victim Identification Team was at work ensuring all the deceased were identified and the families kept informed respectfully, police said.
Names of the dead have not been released but police believe they know the families involved and have contacted them, Commander Griffiths said.
The deceased were from the Roper Gulf and the Greater Darwin regions but police gave no further details of their identity.
A report will be prepared for the coroner on all five deaths.
The tragedy would have a "long and deep impact" on all concerned, including family, friends and first responders, Commander Griffiths said.
Anyone with information should contact police, he said.
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