Rafael San Sebastián Flechoso was having breakfast at the Gwendolyne cafeteria in Guecho when ETA member Jon Bienzobas approached him and fired three shots, hitting him in the head. He was killed instantly. Another terrorist, who was never identified in subsequent police investigations remained outside, covering the attack. He got away in a car with the other terrorists.
The victim was the brother of Federico San Sebastián, general secretary of Iberduero.