Slick roads, speed and inattention were likely factors in an eight-vehicle pile-up on Highway 1 near Abbotsford that closed the eastbound lanes for about 90 minutes on July 20.

A 33-year-old Chilliwack woman was airlifted to Royal Columbian Hospital with serious injuries, while three others who received minor soft tissue injuries were taken by ambulance to the Abbotsford Regional Hospital.

"We got the call at 10:43 a.m. There were four or five Abbotsford Police vehicles on site, and [their officers] did an astounding job," said Const. Blair Fuller of the RCMP Fraser Valley Traffic Services.

The incident began with a relatively minor collision that happened in the eastbound lanes on Highway 1 just east of the McCallum Road interchange, in which a boat trailer side-swiped another vehicle, said Fuller.

"They had just pulled over or it had just happened, and the traffic coming over the hill had to slow down and were hitting the brakes, and that's when the second collision occurred," he said.

Police believe a black 2008 Hyundai Accent then crashed into the back of a dump truck.

Then as a white Pacific Breeze Heating and Cooling service van had stopped or slowed down, it apparently was hit by another truck from the rear and was pushed into a vehicle ahead of it, said Fuller.

In total, eight vehicles were damaged, he said.

The Hyundai was wedged under the rear of the dump truck, requiring Abbotsford Fire Rescue members to cut the female driver from Chilliwack out of the wreckage.

Fuller was encouraged by the fact the woman was still able to move her limbs following the violent collision.

The complicated crash will be under review for some time as police will have to go through several statements, but Fuller said road conditions likely contributed to the second crash.

"We believe it was a combination of the things. The recent heat brought the oil up to the surface of the asphalt and combined with rain makes it slippery. We figure speed, driver inattention and a few mechanical factors may have also contributed," said Fuller.

The incident drew out several first responders, including an air ambulance, up to five Abbotsford Police vehicles, two Abbotsford Fire Rescue trucks, and ambulances - plus six tow trucks to haul away the damaged vehicles.

The freeway was reopened by 12:18 p.m., but the multiple vehicle pile-up caused traffic to back up to 200th Street and created congestion on Huntingdon Road in Abbotsford as drivers tried to avoid the crash scene.