Several high school students taking their university entrance exams in Tokyo were injured in an apparent stabbing on Saturday, Japanese media said.
Public broadcaster NHK said three people were conscious after being injured in the morning when another student attacked them with a sharp object as they gathered to take their entrance exam.
The alleged attacker, a 17-year-old high school student, has been arrested, the Asahi newspaper said.
Half a million high school students across Japan are taking the annual college entrance exams this weekend at hundreds of locations across the country.
The Tokyo Metropolitan Police Department said it could not comment on the details of the attack or confirm any arrests.
Violent crimes are extremely rare in Japan, but there have been a series of stabbings by assailants unknown to the victims.
In October, a man dressed in Batman’s Joker costume stabbed more than a dozen people on a train carriage in Tokyo, sending passengers screaming into the aisles of the carriages and rushing out of the windows to escape.
A few months earlier, a man injured several people in a stabbing attack on a Tokyo commuter train.