MINNEAPOLIS (WCCO) — The University of Minnesota has issued a crime alert after a string of assaults and robberies either on or very close to campus.

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The U of M says four incidents occurred on the intersections of Harvard Street and Washington Avenue, on Washington Avenue on a Metro Transit Bus near the Willey Hall bus stop and at 17th Street and University Avenue near the Armory. All of the robberies occurred between 1 a.m. and 4:45 a.m.

In each case, two or more victims were assaulted and robbed by a group of five or six black men. The description of the suspects is limited, but all of the men are described as between the ages of 18 and 25 years old, one of the suspects had a goatee beard and mustache, and wore a black puffy North Face vest. Other suspects wore orange or red, and black or dark blue sweatshirts.

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Extra patrols will be in place and investigators are in contact with the victims.

“Despite the nature of these robberies, walking with someone is still the best and easiest way to ensure your safety late at night and on the weekends. If you see suspicious behavior or believe you are in danger in anyway, don’t hesitate to call 911,” the University said.

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Anyone with information about these incidents is asked to call the University of Minnesota Police Department at 612-624-2677.