Police say a horrific three-car, triple-fatality smash on the Bruce Highway near Gympie is a likely domestic violence murder and attempted suicide.

They allege a 25-year-old man, who was the only survivor of the multivehicle crash, was known to a 25-year-old female passenger in a Nissan Navara that was chased and rammed onto the wrong side of the Bruce Highway at Federal early on Friday.

He was found “in the vicinity” of the crashed vehicles and is now under guard in the Sunshine Coast University Hospital.

Earlier, north coast regional crime coordinator Ben Fadian said a carjacked Isuzu MU-X involved in the triple fatality was chasing a northbound Nissan Navara, before ramming it into the path of a southbound vehicle.

A 38-year-old woman in the southbound vehicle, a Great Wall, died in the crash.

Detective Superintendent Fadian said a 25-year-old Yandina man was found at the scene with serious head injuries.

A 65-year-old man who was driving the silver Nissan and her 25-year-old woman passenger also died in the crash.

Police said the young woman and the Navara driver did not know each other before Thursday night, but would not confirm whether the man was helping his passenger.

They say the Isuzu was carjacked at knifepoint from a mother and three children who were forced from their vehicle at Young Street in Gympie at 4.30pm on Thursday.

An alert for the vehicle was issued after a man threatened the women and her children as they were getting into the Isuzu MU-X.

The terrified mother got her kids out of the vehicle before handing over the car to the robber. She and her children were unharmed.

Detective Superintendent Fadian said police unsuccessfully tried to intercept the Isuzu on the Bruce Highway at Curra about an hour later.

“At no stage did police try to pursue that vehicle after it decamped from them,” he said.

He said police received reports about 4am Friday of a silver Nissan Navara and a white Isuzu MU-X travelling north on the Bruce Highway at Federal.

“The white Isuzu was trying to ram the Nissan Navara motor vehicle,” Superintendent Fadian said.

The Bruce Highway north of Brisbane remained closed to all traffic on Friday afternoon, after the three-car collision south of Gympie about 4am.

The driver of the stolen car was known to Queensland police.

Detective Superintendent Ben Fadian described it as a complex investigation and appealed for anyone who saw the stolen Isuzu to contact police.

“We also appeal for anyone who was driving on the Bruce Highway between Federal and Noosa turn-off this morning between 3am and 4am and may have seen that vehicle to please contact Crimestoppers,” he said.

“The tragedy is that there are three people now deceased and the ripple effect that has on their families.”

Queensland Ambulance Service’s Sunshine Coast acting director Nigel Jones said it was a challenging event for all emergency services.

“The scene was obviously quite confronting given the mechanism of the forces involved – it was clearly a very high-speed incident involving those vehicles,” Mr Jones said.

“So much so that our paramedics report that the two patients were killed on impact with a third patient, unfortunately, passing away shortly afterwards.”

Southbound lanes of the Bruce Highway are expected to be closed for an extended period, and diversions are in place.

The forensic crash unit is investigating, and no charges have been laid.

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-with AAP