Five men killed in a horror crash in the Kakadu National Park were from the nearby Gunbalanya indigenous community.
Police say they believe speed was a factor when the black Toyota Camry left the road, rolled and hit trees on the Arnhem Highway as it headed towards Darwin on Monday.
The car had drifted off the road and overcorrected before rolling, Commander Matthew Hollamby told reporters on Tuesday.
"At this stage speed appears to be a major contributing factor in the crash but we will also be investigating whether alcohol had a part to play in it as well," he said.
"I don't remember the last time we had a fatal crash that involved five fatalities, it is really bad.
"It has flow on effects for witnesses, families and the police and other first responders as well."
All five men in the car, which was unregistered, were wearing seatbelts but the crash was too severe, Commander Hollamby said.
Northern Territory Government support services are understood to have been sent to support family members and the wider Gunbalanya community, with the death of five people having a devastating impact on a population of about 1200.
Gunbalanya, also called, Oenpelli, has been closed for Sorry Business, which is used to described Aboriginal cultural practices around death.
The NT road toll 2019 is 28, compared to 47 at the same time last year.