Oakland police are urging Craigslist users trying to buy or sell merchandise to use caution after a string of armed robberies originating on the popular website.

Police said that robbers would either create a Craigslist posting advertising the sale of merchandise or respond to users selling merchandise and rob the victim when they arrived to complete the transaction.

Police are advising that people using Craigslist to buy or sell products to use caution conducting business with people they don't know, or when visiting unfamiliar areas.