The agency said the assailant, Tomohiro Kato, 25, from the Shizuoka Prefecture, was arrested and has admitted to the attack.

The agency quoted Kato as telling investigators: "I came to Akihabara to kill people. I am tired of the world. Anyone would do. I came alone."

The Akihabara district is known for its numerous electronics stores, and as a focus of Japanese comic book and video game culture.

Police said five of those killed were men and one was a woman.

An eyewitness interviewed on TV channel NHK said the attacker "was screaming as he was stabbing people at random."

Before the stabbing spree, which took place at around 12:30 p.m. local time (03:30 GMT), Kato ran over three people in a truck, NHK said.