BOSTON (CBS) -- Boston police say seven or eight young teenagers tried to rob a person in front of a Dorchester KFC on Friday night.

The male victim told police he was approached at 10:20 p.m. by a group of male and female teenagers outside the fried chicken chain at 481 Washington St. He said two young men demanded his cell phone and wallet while pointing a knife at him, according to police.

That's when the victim said he had to swing a plastic bag with three cans of beer inside at the group to fend them off.

Officers chased down the group at Claybourne and Park Street and recovered a black pocket knife. Witnesses then positively identified two of the male suspects.

A 17-year-old from Dorchester and a 15-year-old from Randolph were arrested and charged with armed robbery. The 15-year-old was also charged with resisting arrested and assault and battery on a police officer.

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