Police spokesman Harumi Murayama says Monday’s accident occurred in Tochigi, north of Tokyo. The children — five boys and a girl — were aged 9 to 11.

Police say the truck crossed the center line and slammed into the children before crashing into a house. Police arrested the truck’s 26-year-old driver.

Murayama says police are investigating the cause of the accident, but no alcohol was detected on the driver.

Fuji TV says the truck weighed around 12 tons.