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."
At least three people were taken ill at London Bridge station this morning, but the Metropolitan Police said there was nothing to link the cases at this stage.
NEWS: At this stage there is nothing to link the four people taken unwell at London Bridge Station. #LondonBridge
We are at an incident at London Bridge Station treating three patients who have been taken unwell
Delays of up to one hour and 30 minutes on First Capital Connect between Bedford and Brighton, and between Luton and Sutton (Greater London) due to broken down train at Blackfriars.
Also affecting Southeastern services, with delays of up to 45 minutes between Kentish Town and Sevenoaks, and between Luton and Orpington.
Police are appealing after a £2,500 violin was stolen from a Jubilee line train.
The violin belonged to a 42 year-old musician from Motspur Park who was returning home after performing at a London theatre and boarded the train at Stratford at around 11.45pm on Friday 20th July.
He had four bags with him, including the violin. When he got off the train at Waterloo, just after midnight, he noticed his violin was missing.
Detective Constable Andy Jordan said: “Not only is the violin of considerable financial value but it was also of great sentimental value.
The victim has had the 1880’s violin for 30 years, since he was just 12 years-old. He had described knowing the violin so well, it had become like a good friend.”
The violin is full-sized from a German school from the late 19th century, with the label 'Percy Lee 1936'. It is golden in colour with a wide-striped two-piece backplane with a rippled dent near to the bottom. The tuning peg for the E-string is different to the other pegs.
There was a bow in the case, an octagonal stick with silver winding and leather at the handle.
Anyone with information should contact British Transport Police on freefone 0800 40 50 40 quoting reference B5/LUA of 13/09/12.
Service suspended on Stansted Express between Liverpool Street and Stansted Airport due to obstruction on the line.
Southeastern trains between Grove Park and Bromley North have been suspended due to a broken down train. Tickets are being accepted on local bus routes.
The British Transport Police are trying to trace a man after a woman was inappropriately touched on a train from Birmingham to Euston. The incident happened on Saturday 30 June.
The police say the 34-year-old woman was left extremely traumatised by the incident.