A Toronto school angered students and parents when it banned soccer balls, baseballs, footballs, tennis balls and volleyballs from the school grounds, the Toronto Star reported.
Students at Earl Beatty Public School were sent home carrying letters stating that nobody could bring any of the balls to the junior and senior schools after a "few serious incidents" in which staff and students were struck in the playground.
The temporary ban means only Nerf balls or sponge balls can be used by students at the school for now.
School trustee Sheila Cary-Meagher told the newspaper that the most serious incident involved a parent who was hit in the head by a soccer ball, suffering a concussion.
"I think the principal is reacting in a rational way. You don't want anyone to be injured," she said.
But some parents and students object to the ban, arguing that it is excessive.
Chris Stateski said his six-year-old son Jacob was "crushed" when he learned about the ban.
"He [Jacob] said, 'Daddy, what am I going to do with all my friends?' He wanted to change schools," Stateski said.
Anna Caputo, a communications officer at the Toronto District School Board, said the ban was temporary and that the school would monitor the situation closely.
"It's a small playground and 350 students are playing in that playground. There's also a daycare [center on the site] so there are a lot of small children and parents going in to pick up the children," she said.