The drama began when the security guard challenged a teenager on suspicion he was shoplifting in the Morrisons branch in Chorlton, Manchester, yesterday.
Witness Claire Bruchard then saw the guard get chased, and began frantically shouting for shoppers to help.
“I got my phone to ring police and started shouting for people to come and help the security guard,” she told Manchester Evening News.
She said: ”Within seconds of me shouting these seven men just ran straight to him – they were brilliant.”
“Within seconds of me shouting these seven men just ran straight to him – they were brilliant”
“The security guard was incredible and deserves a medal – he looked really shaken up once the guy was restrained,” she added.
Sean Cummins, 41, who was in the fruit aisle, said he heard shouting and admitted he may not have been so quick to to the scene if he’d known about the blade.
He said: ”It turned out she was shouting ‘he has a knife’, which if I had heard at the time I may not have rushed over to.
“I turned my back and went running round and this guy was throwing punches at one or two men who were wrestling him to the ground.
“A woman was on the phone to police whilst shouting out for more help so I went to go and help pin the guy down.”
Sean added: ”It was mostly customers who jumped in to help, I think a lot of staff were shaken up.”
Morrisons staff then placed a cordon around the area so other shoppers wouldn’t be alarmed.
“We kept him home for about 10 minutes before the police arrived,” said Sean.
“It was pretty scary but I guess it’s fight or flight. There were enough people running towards the man that I felt quite confident it would be okay.
“It’s still a bit of a blur.”
Greater Manchester Police confirmed a 17-year-old boy was taken to hospital before being arrested on suspicion of possession of a bladed article and theft offences.
A spokesperson said: “Police were called shortly before 1.20pm on Tuesday 28 May 2019 to a report of a man in possession of a knife at a supermarket on Wilbraham Road, Chorlton.
“Police and emergency services attended.
“A 17-year-old boy was taken to hospital as a precaution before being arrested on suspicion of possession of a bladed article and theft offences.
“Enquiries are ongoing.”