Washington State Patrol Trooper Guy Gill said 23-year-old Joshua N. Sizemore and 18-year-old Amanda L. Madison were tossing large rocks from the trestle near Bridgeport way about midnight.
Sizemore and Madison were tracked down by troopers on the ground with assistance from a State Patrol airplane which captured video of the couple throwing rocks. Investigators said Madison was in her underwear when police caught up with the couple.
Investigators said the couple was playing a stripping game, which the couple in court referred to as "Sex Me", that involved removing an article of clothing depending on burned out headlights on passing cars, but it's unclear exactly how the stripping game tied into tossing rocks off the trestle.
The hit vehicles included a State Patrol cruiser, Gill said. One person was injured when a rock crashed through the window and bruised his arm, but did not need to be hospitalized.
"I think we very possibly could have saved a life," said Trooper Eric Hatteberg.
Both Madison and Sizemore were booked into the Pierce County Jail. In court Tuesday, they both pleaded not guilty to 14 counts of second degree assault.
Madison is being held on $50,000 bail while Sizemore is being held on $40,000 bail.
An infrared camera aboard a WSP plane captured the couple throwing rocks from a railroad trestle.