The West Mercia force said it was aware of a video circulating on social media of a boy being attacked in an “incredibly distressing incident”.
It appears to show a pupil from the Sikh community being pushed to the ground by two other boys and then struck a number of times in the head.
Charlton School said it had taken “swift and appropriate action”.
A statement on the school website said it took place on 13 November outside school grounds and involved a number of its students.
“We have taken swift, immediate and appropriate action, including sanctions and targeted intervention for the perpetrators,” it said.
“A police investigation is ongoing, and we are co-operating fully.”
The school said the parents of all concerned have been contacted and it was working closely with the local Sikh community.
West Mercia Police said: “We are treating this as a hate crime and with the utmost seriousness.
“Our inquiries into the motivation around the incident are continuing and we are working with our local communities to provide reassurance.”