Three passengers at London Bridge station were taken to hospital after they were thought to have a "mystery illness" but it turned out they were probably just wearing too many clothes in improving weather.
The station was closed because of Health Protection Authority guidance, which states that when three people are taken ill with an unknown cause, specialists must be called in.
Firefighters responded to what they thought was a "chemical incident". An Ambulance Service spokeswoman said the patients had been taken to hospital after complaining of feeling "unwell, dizzy, and hot". The temperature in London was 11C at the time.