A 28-year-old man was arrested after allegedly stabbing a security guard outside of a Gaslamp Quarter bar Tuesday night, San Diego police said. The incident was reported just after 9:15 p.m. in front of the American Junkie bar on Fifth Avenue south of G Street, police said. The suspect entered the bar but left a short time later, at which point he allegedly stabbed a 28-year-old security guard who was standing outside “without provocation,” police said. The victim was stabbed four times with a knife but tackled the suspect and restrained him, assisted by others, until officers arrived. The suspect was arrested while the victim, who was conscious and breathing, was transported to a hospital where he underwent surgery for wounds to his neck, shoulder and stomach. The incident remains under investigation.