Police are attending the incident at the Dockside Outlet Shopping Centre.
A local resident told Kent Online: “There was a lot of banging just over an hour ago, I just assumed it was construction workers.
“There was armed police outside The Range who waved everyone back, they moved towards the noise.
“Staff at The Range have been trying to catch everyone and get them into the shop.
“Someone across the way shouted about someone having a gun.
“There’s a police helicopter flying above.”
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