Police are searching for the person they say is tying parachute cords across nature trails on the East End.

According to police, the unknown person is trying to deter dirt bikes and ATV riders from the trails. They say cords are hard to see, but they can cause serious injuries to riders.

Southampton town police say on Aug. 7 around 6 p.m., a 17-year-old was seriously injured in Sag Harbor when the green parachute chord caught him by his neck.  

They say it threw him off his ATV and he needed to be airlifted to Stony Brook Hospital.

"His parents are reporting to us that he is recovering," says Southampton Town Police Det. Lt. James Kiernan. "But he may need another surgery and we are looking to ID the person who put this parachute cord up between the trees."

Ron Yassen walks the nature trails in the Sag Harbor preserve near where the accident happened, and he can't imagine why someone would do such a thing.

"It is quite alarming to find out that people are rigging traps for riders," says Yassen.

Police say there has been an increase in ATV and dirt bike activity in the area in recent months, leading to a spike in complaints from residents.

"Nowhere in the town is it legally permitted to ride ATVs or motorcycles off-road, says Kiernan. "However, nobody can purposely injure another person whether it's your property or not."

Suffolk County Crime Stoppers is offering a cash reward of up to $5,000 for information that leads to an arrest. Anyone with information is asked to call Crime Stoppers at 1-800-220-TIPS.