Shoppers at Westfield Stratford in east London claim to have been locked in the mall after a large disturbance involving a group of youths.
Police were called to reports of youths behaving in an “anti-social manner” at around 3.20pm on Friday.
When they got there items, including coins, were thrown at them.
People took to Twitter to say they were being stopped from leaving the shopping centre.
Four youths were arrested on suspicion of offences under the Public Order Act and affray.
On Friday evening a group of youths gathered on the bridge outside the entrance to Westfield Stratford City. Police dispersed the youths whilst Westfield Security diverted customers inside the centre to other exits. The youths left the area and the centre remained open for business as usual.