SAN DIEGO (CBS 8 / CNS) - Homicide detectives Wednesday were investigating the stabbing death of a young man who was dropped off in grave condition outside a Mission Valley restaurant by three young men who quickly fled.

Officers and paramedics were called to the Denny's restaurant in the 1000 block of Camino Del Rio South about 10:15 p.m. Tuesday to tend to the wounded man, according to San Diego police homicide Lieutenant Ernie Herbert.

"He was dropped off right in front of the business, basically right by the front door of the business, saying 'this guy needs an ambulance. This guy needs to go to the hospital,'" said Lieutenant David Rohowits with the San Diego Police Department. "Since we don't know where this occurred, we certainly don't have any motive for this particular attack."

The victim appeared to be between 18 and 20 years old and died at the scene. His name was not immediately released, according to San Diego police homicide Lieutenant Ernie Herbert.

The young men fled in a green 1990's model Toyota Camry.

Early Wednesday, Homicide detectives were looking into whether the fatal stabbing was linked to a blood trail found in the 300 block of Franklin Avenue at South Bancroft Street in Logan Heights. Further details surrounding the second location were expected to be released later Wednesday morning.

Anyone with information about the stabbing was asked to call police at (619) 531-2293.