A 39-year-old woman and her 8-year-old daughter were killed Saturday night on the Wild Wonder roller coaster when their car slipped backward and smashed into a car that was being loaded for the next ride. Two people in the second car were injured.

Mark Matczak and his two young children were waiting to board the Wild Wonder when the car slid backward.

"It was like, 'Oh, my God, it's coming back down,' " said Matczak, 39, of Tylersport, Pa. "As quickly as I said that, it hit."

Kimberly Bailey and her daughter, Jessica, of Pomona, N.Y., were hurled from the car as it sped backward in the latest fatal incident this summer at the nation's amusement parks.

"This season has been quite saddening in that regard, and it's certainly not normal," said Joel Cliff, spokesman for the International Association of Amusement Parks and Attractions.

Saturday's accident brought the total deaths in the last week alone to four, while Cliff said the average number of amusement park deaths over the past two decades has been two per year.

"I don't have a sense as to what's causing more accidents this year. I think it's just a set of coincidences. I think the industry is fundamentally as safe as it's ever been," Cliff said.

A week ago, a disabled 12-year-old boy died on the Drop Zone ride at Great America park in Santa Clara, Calif., when he slipped out of a harness. A day later, a man who had partially wiggled out of a shoulder harness fell from the Shockwave, a stand-up roller coaster at Paramount's Kings Dominion in Doswell, Va.

On Wednesday, a coaster at Six Flags Marine World in Vallejo, Calif., came to a sudden halt and stranded 28 people for nearly four hours.

As New Jersey safety investigators peered under the cars and tracks of the new, two-story steel coaster involved in Saturday's accident, the boardwalk park where the ride is located, Gillian's Wonderland Pier, was closed.

The Wild Wonder opened July 1 when Gov. Christine Todd Whitman (R) pressed a button to start the ride. She balked at trying it herself, saying she was afraid of roller coasters.