NEW YORK (CBSNewYork)– The NYPD said robbers are using new tactics to make sure you can’t trace your device after they steal it.

A walk along the water at Riverside Park and 72nd Street turned into a frightening one for Ross Kennedy and his friend when they got mugged at 8 p.m. last Wednesday, CBS2’s Ilana Gold reporeted.

“It was really scary,” Kennedy said.

He said two teens on a bench starting talking to them when they suddenly showed knives on their waistbands and demanded their wallets and cell phones from their pockets. The robbery didn’t stop there, the criminals stayed in contact with the victims for longer than most hold-ups.

“The entire time it was happening I was just waiting for it to be over,” Kennedy said.

He told CBS2 the crooks made sure the iPhones they were about to steal couldn’t be traced. They forced the victims to delete the app called “Find My iPhone” and turn off their iCloud settings, preventing the victims from logging into their accounts from another device and tracking the phone’s exact location.

The app is commonly used by people when their phones are lost or ripped off. Kennedy said the thieves also made them hit reset on their phones and wipe them clean for possible resale.

Kennedy said he used a stranger’s phone to call 911, then cancelled the line with his service provider and had to shell out a few hundred dollars for a new iPhone.

Other iPhone users in the area are now concerned about their phone getting stolen this way.

“iPhones are ridiculously expensive,” Ashley Oakley of the Upper West Side said. “I’m a film student. I have so much stuff on it that I need for school.”

Police told CBS2 this is a new tactic crooks are using and they haven’t dealt with many similar cases yet. Officials say if this does happen to you, don’t fight back.

Investigators said Kennedy and his friend did everything right. They admit in a case like this you may never see your phone again, but the device isn’t worth risking your life for.