By Connor Burton

TROUTDALE, Ore. - A group of 30 to 40 teenagers ransacked an Albertson's grocery store Saturday night, stealing merchandise and trashing parts of the store, according to police.

"All of a sudden a mob of kids come walking out and some of them are running," a witness, who did not want to be identified, told ABC affiliate KATU. "I heard Albertsons employees yelling at them."

According to Troutdale police, the large group of teenagers came from Northeast Portland via light-rail public transportation.

After arriving in Troutdale, the teenagers went to an end of school party that they had heard about from one of the teen's friends who was already there.

Bella Mecca, who was hosting the party, called police after a group of people she didn't know arrived at her home.

"I knew it was bad, but I was relieved the police came to get everyone out," Mecca told KATU.

Police say the kids, who were between 13-17 years old, had been drinking at the party that police shut down before the robbery occurred.

After the party was shut down, the teens walked directly across the street and stormed into the Albertson's.

Store surveillance video shows the kids throwing produce, stealing merchandise, trying to break into a cash register and riding around on scooters for the disabled.

"The employees were completely overwhelmed. They had no idea what was going on," said Sgt. Steve Bevens of Troutdale Police. "They are instructed not to intervene during a robbery because protecting the merchandise is not worth risking your life over."

Police do not have exact numbers on how much damage or merchandise was stolen, but they do know that a large amount was stolen.

"Some of the kids tried opening a cash register with some keys they found and others stole merchandise right off the shelves. We don't know how much was taken yet, but we know it was a lot," said Bevens.

After the leaving the store, the teens scattered through the parking lot. They were later found by a responding officer at a local bus stop.

Only one officer was able to respond to the robbery because other Troutdale officers were busy and officers from surrounding towns were also busy.

"When the officer made contact with the group, approximately 20 of the kids started walking towards the officer. Most wouldn't respond to the officer's questions," said Bevens.

The officer asked the kids how old they were and their date of birth several times, only one responded, and kept repeating "14,14,14," as he marched towards the officer.

The officer managed to arrest two of the kids, both age 14. One of the arrested teens was one of the boys seen trying to get money from a cash register, police said.

"At this time we have about 12 names and we still only have 12 arrests," said Bevens.

Flash robberies seem to be a growing trend nationwide. When asked why he think kids commit these kinds of robberies, Bevens said that kids feel like they have all the power.

"Power by numbers. They go in real quick and grab whatever they want. They know no one is going to confront them or try to stop them," he said.