They allege a 25-year-old man, who is under guard in the Sunshine Coast University Hospital, 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.

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 under police guard in Sunshine Coast University Hospital after being found at the scene with serious head injuries.

He said a 65-year-old man who was driving the silver Nissan and a 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 last night, but would not confirm whether he was helping her. 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.

Detective Superintendent Fadian said police had unsuccessfully tried to intercept the vehicle on the Bruce Highway at Curra about an hour after it was taken. “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 remains closed to all traffic after the three-car collision south of Gympie about 4am on Friday.

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,” Det Supt Fadian 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.

WHAT WE KNOW ABOUT THE HORROR CRASH NEAR GYMPIE

THURSDAY

* 4.30pm: A man armed with a knife carjacks a mother and her children on Gympie’s main street

* 5:30pm: Police attempt to intercept vehicle after reports of erratic driving on the Bruce Highway at Curra, north of Gympie. The driver flees in the vehicle

* Police decline to begin pursuit

* 9.30pm: Alert issued for a white Isuzu MU-X with Queensland registration BEC263

FRIDAY

* 4am: Reports of a stolen vehicle attempting to ram Nissan Navarra driven by 65-year-old man with a female passenger, 25, northbound along the Bruce Highway near Federal, south of Gympie

* Nissan crosses onto southbound lanes and collides head-on with an oncoming vehicle driven by a 38-year-old woman

* Three people were pronounced dead at the scene

* The driver of the stolen car, a 25-year-old man from Yandina, is taken to hospital with serious head injuries

* The highway remains closed and traffic diversions in place.