A teacher from Crawley College, West Sussex, did not hesitate and wrestled the alleged gunman to the ground outside the college building, the Scottish Sun reported, uploading footage of the scene.
Several other members of staff also rushed to help, it was reported.
Eye-witnesses said the man was armed with a handgun and wandered around the college and surrounding area firing shots while allegedly telling the students “to run”.
Police arrived at the scene in the afternoon after two staffers were reportedly injured. An 18-year-old man was nabbed, with a firearm and a knife seized by the cops.
Nobody was shot, but two people were injured. The brave teacher – the first responder – reportedly had his hand slashed open with a knife.
Neither of the injured is thought to be seriously hurt, and staff and students have been evacuated from the college, Sussex Police said.
Counter-terrorism police units are working with local officers and "all lines of inquiry are open," law enforcement added.