BOW, N.H. – One person was killed in chain-reaction crashes on icy Interstate 93 Saturday that involved up to 100 vehicles, including three school buses, and shut down the highway as thousands headed north to the ski slopes.

Witnesses said it started around 8:20 a.m. when one car spun out on ice on the northbound side of the highway near the Interstate 89 interchange. After that, it was bedlam.

“We slowed down and immediately got rear-ended, then we hit a truck,” said Marianne O’Sullivan of Haverhill, Mass., whose vehicle was one of the first to be hit.

Another driver at the initial accident said she saw cars spinning and tried to stop.

“I started to apply the brakes and nothing happened,” said the shaken driver, who did not want to be identified. “I ended up off the side.”

Concord Fire Battalion Chief Kenneth Folsom said about 100 vehicles were damaged in some way, and four people were taken to the hospital, all with minor injuries.

The fatal crash occurred far back in the traffic jam caused by the initial crash, when a van rear-ended a tractor-trailer, Folsom said.

The van driver, Alan Drew, 55, of Loudon, was pronounced dead at the scene. Troopers said the tractor-trailer was stopped in the center lane.

Three school buses were among the vehicles involved. No one on the buses was hurt. A firefighter said the buses carried children and adults. It was unclear whether they were on school-related trips, or perhaps headed to the slopes.

“We checked over 50 people” for various injuries, Folsom said. Many were bumped and bruised, he said, as tow trucks worked around him to untangle the wreckage.

Cars skidded into guardrails, down embankments or into woods. Others spun around and were hit head-on by vehicles that had been following them. Some were sandwiched – being rear-ended after hitting cars ahead of them, or hit from the rear and pushed into stopped traffic ahead.

The initial series of crashes involved 20-30 vehicles, police said. More collisions occurred as traffic slowed and drivers skidded into each other miles before the initial crash.

O’Sullivan, who was headed to the slopes, said the highway was clear south of the Hooksett Toll Plaza, but turned icy north of the tolls. The conditions changed, she said, but the speed of drivers didn’t.

“I was just saying ‘Geez, we should slow down,”‘ because of the sudden ice cover, she said. “We were just discussing it” when they saw the spinning car up ahead.

It was sunny at the time, after a night of snowfall, and the road at the initial accident scene was covered with patches of hard-packed ice.

The storm caused many other accidents, including one on Route 9 in Keene Friday night in which a rescuer at a crash was injured when another car skidded into him.

Police said Gordon Rudolph, 36, of Spofford, a member of the Spofford Fire and Rescue Battalion, was helping a driver whose car had flipped onto its side in a culvert when the second car skidded at the same spot. Rudolph suffered leg and torso injuries when he was pinned between the two cars.

Another driver was hurt at the same spot moments later when she skidded into a car that was slowing down at the accident scene.