ST. LOUIS, Mo. – Three people were robbed and one of them shot after confrontations with someone posing as a cell phone seller using the LetGo app. According to our partners at the St. Louis Post-Dispatch, Normandy police are investigating two of the incidents.

The department tweeted out a warning urging residents to avoid buying electronics from strangers using the app.

LetGo is an app where people can buy and sell used items locally. But in three different encounters, the situations appear to have turned dangerous. Normandy police say two of the robberies happened in a residential area on Bermuda Drive and the third happened in nearby Ferguson.

Investigators say around 5 p.m. Sunday, a victim came to the Normandy Police Department saying they had been robbed on Bermuda after responding to a cellphone ad on LetGo. While the officers were writing that report, another victim called from the same location saying they had been robbed and shot.

That victim’s injuries are non-life threatening.

The Ferguson incident happened not long before the robberies in Normandy. Police believe the same person is behind all three robberies. They are encouraging people to meet sellers in public locations.

The app itself also advises that as well. The app also says buyers should consider bringing a friend to transactions.