A woman attacked two passengers with a blunt instrument on a subway train in Yokohama near Tokyo on Tuesday, causing slight head injuries to the female victims, police said.

The perpetrator fled following the attack, which took place around 2 p.m. on the Yokohama Municipal Subway Blue Line bound for Shonandai Station, and remains on the run, the police said, adding they suspect the weapon used was a hammer.

Photo shows a train of Yokohama Municipal Subway Blue Line on June 10, 2019. (Kyodo)

The woman, who appears to be in her 60s and around 150 centimeters tall, suddenly hit a 71-year-old woman and an 18-year-old high school girl, both of whom were seated, according to the police.

The victims reported to the police after getting off the train at different stations.

The incident follows a string of attacks on trains and station premises in the Tokyo area in recent years, including one carried out on Halloween by a man dressed as Batman villain the Joker in which 17 people were injured.