Police at the scene. Tanks to Stephen Dixon for the picture.

Witnesses have reported seeing armed officers at the scene.

Stephen Dixon, whose flat overlooks the scene, said it appeared police were dealing with a hostage situation in the Coral bookmaker's office at the centre

Police at the scene. Tanks to Stephen Dixon for the picture.

"We heard a commotion going on, which was the police officers shouting.

"It looks as if there's been one member of staff released so far."

The police helicopter was also at the scene.