Japanese police suspect that the assailant in a weekend fatal knife attack at a fast food restaurant in the southwestern prefecture of Fukuoka may have perpetrated the assault indiscriminately.

The man attacked two junior high school students at a McDonald's branch in the city of Kitakyushu on Saturday night. A 15-year-old girl, Nakashima Saaya, died. The other victim, a 15-year-old boy, is conscious.

The man is described as around 40 years old and about 170 centimeters tall. He remains at large.

Investigators quote the boy as saying the attacker was a total stranger. But they say it remains unclear whether the girl had any acquaintance with the assailant.

Investigators say she had not sought any consultations from police. They add that nothing has been stolen from the scene of the assault.

Police say the girl died from blood loss after having been stabbed in the abdomen.

They say she bore no marks of wounds she would have suffered if she had tried to protect herself. They say this indicates she was attacked in a short span of time.

Kitakyushu City's board of education has decided to keep the school that was attended by the victims closed on Monday and have asked police to step up patrols and other security measures.