The Met Police has referred itself to the police watchdog over the treatment of a woman arrested in front of her son in Croydon, south London, after wrongly being accused of bus fare evasion.
Video footage of the mother shouting as two officers handcuffed and held her provoked criticism on social media.
The Met said she was later released when it was confirmed she had paid for her ticket.
The force added the video was a "snapshot of a wider incident".
The police officers were working together with Transport for London (TfL) inspectors on Whitehorse Road, Croydon, when the incident happened on Friday morning.
The Met said one woman left the bus after not complying with a revenue inspector's request to check that she had paid her fare.
According to the Met, when asked to stop by police she attempted to walk off and became "abusive".
As a result, the force said she was arrested on suspicion of fare evasion and detained.
She repeatedly asks one of the officers to let go and says "I haven't done anything wrong", while a member of the public films what is happening and asks why she is being arrested.
Officers did eventually check her ticket, which was valid. She was then unhandcuffed and released.
https://www.bbc.co.uk/news/uk-england-london-66290457