AN ELDERLY man from Dalby is lucky to be alive thanks to the heroic efforts of bystanders who helped pull him from his burning vehicle, only seven seconds before it exploded on the Wide Bay Highway this morning.

Gympie family, Kellie Munn and her partner Josh Morris and 16-year-old son Dylan Morris were travelling to Stanthorpe when they arrived on scene at the horrific head-on collision, near Kilkivan.

They described it as an absolute nightmare with images and sounds they will never forget.

"It was a terrible head-on. Our first thought was that somebody is dead up here," Ms Munn said.

"The ute was engulfed very quickly and the next thing, we see the paddock is alight.

"We thought the fire would spread towards the other car, so we were panicking quite a bit."

A Sunshine Coast woman was one of the saviours of the day supplying the lifesaving tool of a small bladed knife which was used to cut the seatbelt, so Josh and his son could free the man.

They also had to remove him from underneath the steering wheel.

Within seconds of carrying the injured man out of the car - Dylan carrying the legs, and Josh carrying the upper body - a gas bottle on the back of the Ute's tray exploded.

A Hervey Bay family laid injured in the crushed Pajero.

"Josh went to the other car and ripped the passenger door open, moved stuff off her lap," she said.

The second car contained a family, with a woman in her 80s severely crushed in the passenger seat.

Fire and rescue officers took two hours to free the woman using the jaws of life to remove the doors and push the dash forward.

She was airlifted to the Sunshine Coast University Hospital in a critical condition, but it was upgraded to serious, but stable last night.

Her husband managed to escape the vehicle with minor injuries and another woman in her 40s received minor injuries.

They were both taken to the Gympie Hospital in a stable condition.

Ms Munn said she was incredibly proud her partner's efforts alongside others to rescue the injured man.

"It was great seeing them all work together, risking their own lives to save them," she said.

"We will never forget this crash. Dylan said he couldn't get the image of the women's leg out of his head."

Fire and Rescue area manager Kent Mayne said all passengers were lucky to survive.

"This is actually a significant and a severe crash and everyone who has survived has been very lucky to survive," he said.

"We're pleading with people to take care and slow down on the roads - we're not at the end of the school holidays yet and unfortunately we're just having more and more of these road crashes with our region."

Kilkivan officer-in-charge Hans Van Kempen said the bystanders actions saved the day.

"Great motorists who have assisted have dragged an older man from a Ute just prior to it going into flames. They've done an outstanding job to remove him," he said.

"Outstanding members of the public who have come on scene first have been able to drag the older gentleman from the ute before it burst into flames and have assisted the other ones in the pajero until emergency services arrived.

"The ability for the passerbyers to drag the man out, I would dare say has saved his life."

The Forensic Crash Unit is investigating the crash.