Police said the incident began at about 1:45 a.m. when the victim, a man in his early 20s, was walking with his girlfriend in the 2200 block of First Avenue.
The couple got into an argument with a group of four or more men, and the victim then attempted to walk away from the men toward his car in the 2300 block of First Avenue.
At that point one of the men in the group stabbed the victim in the chest. He collapsed to the ground and 911 was called.
The victim was whisked to the hospital, where he died soon afterward, said Seattle police spokesman Mark Jamieson.
The group of men fled the scene in a gray truck or SUV before police arrived, heading north on 1st Avenue.
Officers conducted a search of the area, but were unable to find the suspects or the vehicle, Jamieson said.
Witnesses at the scene told police that there was a disturbance and possible fight among several people outside the Tia Lou nightclub, in the 2200 block of First Avenue, a few minutes before the stabbing. Witnesses also say that onlookers not involved in the fight or stabbing may have captured the disturbance on their cell phones.
Detectives would like to see any video footage of the fight, as it may assist in the investigation. Anyone with information or who has video of the disturbance is urged to contact the Seattle Police Homicide Unit at (206) 684-5550.
The investigation continues.