BOSTON (AP) — Authorities say a 25-year-old man has been fatally stabbed after apparently being involved in an argument on a Boston bus.

Police did not immediately release the name of the man, who was stabbed Wednesday afternoon near the Dudley MBTA stop in the Roxbury neighborhood.

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An MBTA spokesman said the man had been involved in an argument on the bus, but was stabbed after the parties got off.

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The killing was the fifth homicide this week in the city. Three women were fatally shot on Sunday as they sat in a car in the Dorchester neighborhood. Also on Sunday, a man was fatally shot in the Roslindale neighborhood.

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Copyright 2012 The Associated Press.