An 11-year-old girl slashed a female classmate to death with a box-cutter Tuesday in a shocking attack in an elementary school in southern Japan, police said.

The lunchtime assault happened in a classroom in Sasebo (search), 650 miles southwest to Tokyo, an official with the Nagasaki Prefectural police said on condition of anonymity.

Police in Sasebo said the victim suffered wounds to the neck and arms. She was slashed by a retractable knife used to cut paper and boxes, police said.

Police identified the victim as Satomi Mitarai, 12. The name of the attacker was not released, in accordance with Japanese legal protections for juvenile offenders.

Mitarai's bleeding body was discovered in a third-floor classroom by a teacher who called police. Agents quickly apprehended the young suspect, who was being questioned.

Prefectural police said the suspect had confessed, though they did not yet have a motive.

"I can't understand at all how it happened," said the victim's father, Kyoji Mitarai, who told reporters his daughter always seemed to get along with her classmates.

"When I arrived, Satomi was already lying there collapsed. I couldn't believe what I was seeing before my eyes," he said.

The killing was committed in a classroom that was empty at the time, while students took their lunch in other rooms.

Increasing violence in Japan's schools and among youth has been a rising concern in recent years.

Last July, a 12-year-old boy was accused of kidnapping, molesting and murdering a four-year-old in the southern city of Nagasaki (search). In the same month, a 14-year-old boy was arrested for beating a 13-year-old classmate to death in Okinawa (search).

While violent crime, including murder, assault and robbery, is still relatively rare in Japan, juvenile delinquency is on the rise, according to police statistics.

The Japanese government in 2002 lowered the age for which juveniles can be prosecuted as criminals from 16 to 14.