A London Ambulance Service spokesman said:
"We were called at 8.39am today to reports of a patient taken unwell at London Bridge station.
"We sent two ambulance crews, a single responder in a car, our hazardous area response team and a duty manager.
"Our staff have assessed four patients at the scene who were taken unwell. Three of the patients have been taken to hospital."
More top news
Thousands more partygoers headed to the second and final day of the Notting Hill Carnival.
London developers have got the green light to build a 25m 'sky pool' between two buildings in Nine Elms.
A top cop has been spotted joining in with rank and file police officers dancing at Notting Hill Carnival.