24 people with minor injuries have been taken to St Thomas' hospital, a London Ambulance Service spokesperson has said.
Several others in a more serious condition are being treated at the scene of the crash.
More top news
London Ambulance Service has more paramedic job vacancies than anywhere else in England.
Hundreds of people march for more affordable homes and control private rents in London.
Police proposals suggest that all frontline police officers should have the option of arming themselves with Tasers.