Armed police have been called to Glades shopping centre in Bromley after reports of a stabbing and a man seen holding a machete.
A video posted on social media shows shoppers running away in panic during the Boxing Day sales.
Some are seen leaping over the side of an escalator to escape.
There were also images of police arresting a man. One officer appeared to be holding a 2ft-long machete.
Read more: Sky News