A 15-year-old Alexandria student was stabbed twice yesterday afternoon by a 16-year-old on a school bus taking them home from vocational training, according to police.

The victim was treated at Alexandria Hospital for wounds in his back and was listed in stable condition less than three hours after the incident. He was transferred to the Northern Virginia Doctors Hospital in Arlington for further treatment, according to hospital officials.

The suspect, who was identified by other student passengers on the bus, fled and had not been arrested as of early last night, according to Alexandria police. Police said they had not determined a motive, but said drugs did not appear to be a factor.

The incident occurred about 2:30 p.m. near Kenmore Avenue and North Van Dorn Street, when two students got into an argument on the moving bus, according to police and school officials.

Robert M. Harper, assistant superintendent of the school system, said "two guys got in a fight, apparently one turned and he got stabbed twice. It appeared to be a kitchen knife."

Harper said he could not remember a similar incident occurring in the Alexandria school system in recent years.

The students are among the 110 youths enrolled in Alexandria's full-time vocational education program based in the Minnie Howard Administration building on Braddock Road, according to Harper.

Harper said about 10 vocational students were on the bus when it neared the end of its westbound route near Hammond Junior High School on Seminary Road. The driver pulled to the curb immediately after the stabbing, Harper said.

"The driver saw it and everyone got off, including the student who had been stabbed. One of the students ran over to Hammond and got the principal, and they called the police," Harper said.

The suspect escaped into the Seminary Towers apartment complex, Harper said.

Harper said the suspect could face several weeks' suspension or permanent expulsion from school in addition to any criminal charges. The assault constitutes a felony and could be prosecuted by the Commonwealth's Attorney's Office as an adult or juvenile offense.