CHARLOTTE, N.C. -- Charlotte-Mecklenburg Police are warning buyers and sellers of online merchandise about the dangers they can face during these transactions.

They've just started to see this year how frequently crimes from them are taking place.

Buying or selling merchandise from mobile apps is pretty convenient, but the exchange in-person has proven to be pretty dangerous. CMPD said in 2016 they've had 52 criminal cases, including 10 armed robberies, from the "OfferUp" app from

You can post items on there you're looking to sell, someone offers to buy, then you set up a time and place to exchange money and the item. Before you get in the car and go make one of these exchanges, police want you to keep a few things in mind:

Across the Charlotte area, most of the crimes have taken place in the north, and university divisions.

"This is nothing new," said Lieutenant Jim Morrison. "Going forward there will be more technology coming down the pipe. It's going to continue."

If the offer seems too good to be true, that should be a red flag. So make sure you do the sale during the day and at a safe, secure place, like right outside a police station.

Monroe Police also sent out a warning that scammers are creating fake mobile apps. They're hoping you'll download them to your phone, and submit credit card information for that they can steal.