The pane, which was part of a panel surrounding the escalator, shattered on to the lower level outside Supercuts hairdressers and sport nutrition store GNC.
Traders and shoppers said it was lucky no one was hurt in the incident.
One woman, who does not want to be named, was sitting on a bench on waiting for her daughter when the pane fell.
She said: “I was a couple of feet away when there was an almighty crash. There was glass everywhere. There could have been a very serious injury or worse.”
Two workers from GNC ran out to ensure shoppers had not been hurt.
Store assistant, Dean Storey, said: “A couple of people were sitting on the benches near where it happened.
“One young girl was sitting closer than the others. I rushed to see if she was OK. Luckily she was and no one got hurt.”
The area was closed off for an hour while the site was cleared, before re-opening at 12.40pm.
Ian Clark, manager of the Eastgate Centre, said: “The glass is toughened, which is designed to crumble into small granular pieces with no sharp edges, and no one was injured as a result of the glass breaking and subsequently falling to the floor.”