A man in a station wagon sprayed groups of junior high school students in Fujisawa, Kanagawa Prefecture, with a powdery fire extinguishing agent Wednesday morning, causing 66 people to seek hospital treatment, police said.
The 66 victims, mostly students at Takakura Junior High School, complained of nausea and pain in their eyes, but none of the cases was serious, police said.
The school called parents and guardians together for an emergency meeting and had students go home in groups.
According to police, a blue station wagon, carrying the passenger and a male driver wearing a navy blue mask, approached students from behind as they walked to school around 8:05 a.m.
Investigators quoted witnesses as saying the passenger used what appeared to be a hose to spray the white powder at several groups of students before making a U-turn and driving away.
Police probing the assault said the agent can be purchased at stores.
According to school officials, there were instances last Friday and Tuesday in which cars had harassed students near the school, including by suddenly lurching toward them or backing up toward them.