Two teens are accused of setting off sophisticated pipe bombs Sunday at Tallman Mountain State Park in Sparkill.

Police said parkgoers called 911 because they thought they heard gunshots. However, authorities said it was the sound of two of the devices being detonated. The third device was found at the scene, investigators said.

"This was not a common ordinary lighter fuse ... type of device," said Rockland County Sheriff Jim Kralik. "This was much more sophisticated."

Officials said the bombs were especially dangerous because they were filled with ball bearings that could have killed people.

The boys, ages 14 and 16, are cousins from Union City, N.J. The 14-year-old was released to his family. Authorities plan to prosecute the 16-year-old as an adult. He is charged with criminal possession of a weapon and endangering the welfare of a child.

For the police news conference about the arrests, go to channel 612 on your digital iO cable box and select iO Extra.