Officers rushed to a quiet residential area of the Vancouver Island city at 12:30 a.m. Tuesday following calls about an assault in progress.
Const. Gary O'Brien says a caller reported seeing a man run off, leaving the teenaged victim with multiple, life-threatening stab wounds requiring immediate surgery.
A police dog tracked a suspect to the yard of a nearby home and a 19-year-old man is now in custody, expected to be charged with aggravated assault.
O'Brien says the stabbing was not random and the 16-year-old knew her attacker, but the exact nature of the relationship is still under investigation.
Police have made arrests in a series of unrelated, violent incidents in Nanaimo in less than a week, beginning with the fatal shooting of two men and the wounding of two more at the Western Forest Products sawmill last Wednesday and a stabbing that critically injured a local man the following day.