The Los Angeles County Sheriff’s Department is sharing safety tips for online sellers after a person was robbed at gunpoint while trying to sell a used cell phone.

The armed robbery happened at an undisclosed location in Palmdale Thursday.

The victim, the Sheriff’s Department said, met up with their attacker to exchange a cell phone that they agreed to sell on the app OfferUp.

During the exchange, one or more people pulled out a firearm and forcefully took the phone from the victim.

The Sheriff’s Department said these types of robberies happen with some regularity and are “completely preventable.”

Officials urge anyone in the Antelope Valley looking to complete an online sale to do so at one of the dedicated parking stalls at either the Palmdale or Lancaster Sheriff’s Department stations. Those parking stalls are under 24/7 surveillance and are considered a “safe, public place to conduct your sale,” the Sheriff’s Department said.

If you aren’t able to make a sale in one of those stalls, it’s encouraged to make a sales handoff in a highly-visible public place. Police, sheriff, fire department stations or other busy public areas are good places to consider.

It’s also suggested to never meet with a stranger alone — instead, bring a friend or family member along with you.

Additionally, people are urged to be diligent when using a sales app like OfferUp or websites like Craigslist and Facebook Marketplace.

“Criminals use these sales platforms to find vulnerable victims,” a post from the Sheriff’s Department reads. “Following these steps can help prevent these types of robberies and keep you safe.”