Four people were injured on Friday in a stabbing attack on a train in Tokyo, with the suspect captured after fleeing the scene, leaving his weapon behind, local media said.
Violent crime is vanishingly rare in Japan, and the reported attack comes with the capital on heightened security alert as it hosts the Olympic Games.
The attack took place on an evening commuter train in Tokyo's Setagaya ward, in the west of the city, and two of those hurt sustained serious injuries, public broadcaster NHK said.
The site is several kilometres from the venue of Olympic equestrian events.
The train company said on its website that it had suspended some services after "an assault in a carriage."
Local station TBS said the man was captured after leaving the scene of the attack. There were no immediate details about the attacker or a motive.
Local police and emergency services declined to comment on the reports.
Japan has strict gun laws, but there are occasional violent crimes involving other weapons.
In 2019, a man killed two people including a schoolgirl and wounded more than a dozen in a rampage that targeted children as they waited for a bus.
And in 2018, a man was arrested in central Japan after stabbing one person to death and injuring two others aboard a bullet train.