There are dozens of apps that now specialize in helping you offload your stuff for quick cash. But it pays to be careful, and not just so you can make sure you're getting a good deal: In a new report from the Consumer Federation of America, state and local agencies say, when it comes to people attempting to buy or sell their items online, they're increasingly dealing with robberies.

Apps like Facebook Marketplace, OfferUp and LetGo promise to eliminate a middleman, offering buyers and sellers the chance to arrange their own terms. But unlike older platforms like eBay, through which you typically mail the item to a buyer, newer apps prioritize local buyers to avoid shipping fees, so the parties often make the exchange in person.

All three apps have comprehensive safety guides online and OfferUp even provides users with a way to search for safe meet-up spots. But that sometimes isn't enough to prevent problems.

Across the U.S., local police departments report incidents where unsuspecting consumers were placed in dangerous situations after agreeing to meet up in-person to buy or sell items like phones, video games and watches. Last month, a woman in Columbus, Ohio, attempting to sell a camera and lens was robbed at gunpoint when she went to meet the prospective buyer she interacted with on LetGo.

Earlier this month, a man agreed to meet a St. Louis couple through Facebook Marketplace to purchase a $250 video game. But when Brittany Huddleston and Taylor Boyd arrived at the meeting spot in the nearby park, the man pulled a gun on them and demanded the game, according to the local ABC news affiliate.

The police in the Philadelphia suburb of Chester started tracking this kind of crime in January 2017. In the first year, they logged roughly 28 online robberies, 25 of which involved a weapon, reports the Philadelphia Inquirer.