Ottawa County Sheriff Terry Durborow said the truck jumped a guard rail on Interstate 44 in northeast Oklahoma and fell into the Spring River. The truck was partially submerged.
Durborow says from five to eight people were in the truck.
"This is a fall of 80 feet or better ... that alone is a very dangerous type of crash. This is a very traumatic crash," said Oklahoma Highway Department spokesman Lt. George Brown.
Motorists who witnessed the accident said they peered over the side of the bridge and spotted six victims outside of the truck in the icy water and another two people inside the vehicle, Brown said.
"The rescue teams got a small boat, hoisted it down in the water and started the recovery," Brown said.
Survivors were taken by ambulance and helicopters to nearby hospitals, he said.
"The ground temperature was 11 degrees below zero, so it would take second to become hypothermic in this water and ice."
Hundreds of motorists were stranded on Interstate 44 during the huge snowstorm that barreled through Oklahoma and much of the nation this week, and crews were still working Wednesday to clear the westbound lane.
Brown declined to speculate about whether officials may have opened the westbound lanes too soon.