Security camera footage shows that the apparent suspect in a random stabbing on a Tokyo street followed her victims shortly before the incident on Saturday night.

A 53-year-old mother and her 19-year-old daughter were stabbed with a kitchen knife on a street in Tokyo's Shibuya Ward. They suffered serious injuries. A 15-year-old junior high school student living in Saitama Prefecture, north of Tokyo, was arrested on suspicion of attempted murder. She was sent to prosecutors on Monday.

Security camera footage believed to have been taken several minutes before the attack shows a person thought to be the suspect walking about two meters behind the victims.

Tokyo police say the girl is thought to have headed for the capital by train and walked from Shinjuku Station to the scene.

Police say the girl told them that she had randomly targeted the mother and daughter after spotting them on the street. She said she had been looking for an empty alley to kill someone.