Forty-six people, including schoolchildren, were taken to hospital on Saturday morning following an accident involving three buses and a motorcycle on Tokyo's Metropolitan Expressway, the fire department said.
They were taken in for minor injuries after a motorcycle crashed into the side of a bus ferrying children and their caretakers to an aquarium around 8:40 a.m.
The driver of the bus slammed on the brakes, causing two buses following it to rear-end the vehicle in front, according to police.
The man driving the motorcycle apparently tried to change lanes in a no-change zone, the police added.