A hammer attack injured at least eight people on a Tokyo university campus on Friday before the attacker was detained by police, Japanese media reported.
None of the injured lost consciousness, public broadcaster NHK said, adding that the attack took place on the campus of Hosei University in the Tama district in the western suburbs of the Japanese capital.
Jiji Press reported that a student in her 20s was detained and is suspected of involvement in the attack.
Police did not confirm these details when asked by AFP news agency.
Live footage broadcast by NHK showed a long line of emergency vehicles and ambulances heading towards the university campus in the Machida district.
Violent crime is rare in Japan, a country with strict gun control laws.
However, stabbings and even shootings, such as the attack that killed former Prime Minister Shinzo Abe in 2022, do occasionally occur in the country.
An elementary school student died after being stabbed in December, and another was injured last week at a McDonald's restaurant in southwest Japan, an attack for which a man was later arrested.
In 2019, two people, including a schoolgirl, were stabbed and killed, and more than a dozen injured, in the city of Kawasaki, in an attack perpetrated by an assailant who targeted children waiting for a bus.
A 51-year-old man then killed himself by stabbing himself in the neck.
