A double fatality on the Sunshine Coast Motorway after a truck crashed into three stationary cars that were stopped at by a traffic controller.

John McCutcheon / Sunshine Coast Daily

THREE lives were lost in just three hours on Sunshine Coast roads yesterday.

At least another five people are in hospital with serious injuries.

The true number of people affected by yesterday's loss will never be known.

Peak-hour traffic at the northern end of the Coast became a parking lot, with the Sunshine Motorway and David Low Way closed by the crashes for more than four hours.

Witnesses, emergency service workers and the media were stunned to see four separate vehicles crushed together on the Sunshine Motorway, about 2km south of Pacific Paradise.

The accident happened just after 2.15pm.

Four cars had stopped under the direction of a female traffic controller, in a 40kmh zone of the new motorway section, when a concrete pumping truck ran into them from behind.

A Subaru Forester carrying four people - including a 15-year-old girl and her 18-year-old sister in the back seat - took the brunt of the crash.

Both girls were killed.

Their vehicle was crushed between the truck and a small Hyundai in front of it.

The girls' father, who was behind the wheel, and a family friend in the front passenger seat were also hurt.

The driver of the Hyundai was injured when the vehicle meshed with the white Holden ute stopped in front of it.

A small, dark-coloured vehicle had been stopped in front of the ute, but it did not stay at the scene and the driver headed off after the crash.

Police want to speak to the vehicle's occupants, who were described as an elderly couple, about what they may have seen.

It was difficult to distinguish where one vehicle started and another ended.

The injured, including the teenage girls' distraught father, who is believed to be from Brisbane, were rushed to Nambour General Hospital with serious but not life-threatening injuries.

The traffic controller is believed to be unharmed but severely shaken by the accident.

The 50-year-old truck driver, who lives at Kiel Mountain, was interviewed by police at the scene.

Skid marks from the Isuzu 500 truck went for more than 20 metres.

Both the truck driver and his passenger escaped serious injury.

The second fatal collision happened just after 5pm.

Police had just received information about a silver vehicle leaving the scene of a crash on David Low Way at Marcoola when they heard reports that it was involved in a fatal head-on crash just 400 metres along the road.

Two adults and a young child inside a station wagon had a lucky escape when the 87-year-old driver of the silver sedan drove up on to a roundabout and hit their vehicle.

The silver vehicle then ploughed into bushes.

Police believe the driver accelerated back on to the road, and continued towards the Town of Seaside.

Witnesses told police the speeding, silver vehicle then veered on to the wrong side of the road and collided with a Holden Statesman carrying three people.

The silver sedan flipped and ignited. The elderly driver is believed to have died instantly.

The three people in the Holden were rushed to Nambour General Hospital. They were in a serious condition.