
The boy was detained following reports of three people being injured at Birley Community College in Sheffield, South Yorkshire Police said.
Officers responded to reports of an incident “involving a sharp object” at around 8.50am.
Two adults were checked at the scene after suffering minor injuries, the force said in a statement.
A child was also checked over after being assaulted, it added.
Last Friday, a 13-year-old girl made a first appearance in court in Wales on three counts of attempted murder after two teachers and a pupil were stabbed at a secondary school.
The attack occurred at the Amman Valley School in Ammanford, north of Swansea, just after 11am last Wednesday.