Police armed with guns tackled a grenade-throwing man and his accomplice in a bus hijack enactment in Tokyo on Wednesday after the Brussels airport and subway bomb attacks that killed 32 people.

The Emergency Response Team, a select group from members of the country's anti-firearms squad, is stepping up preparations before the nation hosts the Group of Seven summit in late May.

The police have increased patrols and are stationing more staff at the nation's biggest airports following the Belgium and Paris terrorist attacks as the country attempts to gird its defenses against assaults from groups such as Islamic State.

The practice drill took place in a new bus terminal at Shinjuku Station, the world's busiest train hub, with more than half a dozen police apprehending the two hostage takers and releasing the passengers.

"The terror threat is affecting the whole world," Takahiro Tezuka, the head of Harajuku Police Station, said after the drill. "Soft targets such as transport hubs are drawing attention."

The Emergency Response Team, formed last year, is a 24-hour response unit that specializes in hostage situations and attacks. The team is similar to the Special Weapons and Tactics teams in the U.S., known as SWAT, Tezuka said.

Japan's largest terrorist incident was a sarin attack on subways by members of the Aum Shinrikyo cult in 1995. The attack killed 12 people and sickened thousands.