NBC NATIONAL NEWS — An Oregon convenience store owner has released security video showing a flash mob-style robbery of his business last weekend.

A group of 20 or so walked into the Portland-area convenience store and took about $200 in merchandise before running off.

The group went up and down the aisles grabbing what they wanted and forcing the store's employee to stay away.

The owner says some of them became involved in a confrontation with the employee as they were leaving, which could make the crime more serious than simple theft.

Police say they have no doubt this was an organized effort.