A Japanese man drove a minivan directly into a crowd of pedestrians out for New Year's celebrations in what he said was retaliation for the "death penalty", police said.
A 21-year-old suspect, named as Kazuhiro Kusakabe, was arrested and being questioned, Tokyo Metropolitan Police said.
The street was closed to vehicular traffic at the time as it was expected to be crowded with people, including those making New Year's visits to the nearby Meiji Shrine, one of the biggest Shinto shrines in Japan.
The people injured ranged in age from teenagers to people in their 50s, including a male university student who remains in critical condition.
NHK TV footage showed a small van with the entire front end smashed and officers and ambulance workers rushing to the scene.
Police told broadcaster NHK that he initially told then he had conducted a terrorist act, but then later claimed it was related to executions.
The attacker, who reportedly drove from the western region of Osaka, told investigators he planned to burn the vehicle, according to private network Fuji TV.
One witness told NHK the scene was "ghastly".
A container with kerosene inside was found inside the rental vehicle, local media said.
Police cordoned off the street, which, during the day, is packed with tourists.
One college student sustained serious injuries during the attack and was undergoing surgery, the police spokesman said.
A ninth man was slightly injured after the driver had allegedly struck him after getting out of the auto.
A police spokesman said a man has been detained over the incident and that he had described the incident as an "act of terror", Reuters reported.
Takeshita Street is packed with small shops and is considered the centre of youth culture and fashion in Japan, attracting tens of thousands of global tourists every day. Hundreds were heading to the shrine to pray for good luck, heralding in the New Year.
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