Baylis Road was sealed off and the Bakerloo line was suspended between Piccadilly Circus and Elephant & Castle on Sunday for a major emergency services exercise at Lambeth North.
Firefighters outside the closed station
Bakerloo line general manager Penny Hazell said: "With a real incident, there would be no advance warning. That is why details are not revealed, enabling LU and the emergency services to treat the exercise as if it were actually happening. By doing this we are able test our emergency plans and improve upon them where necessary.
Emergency vehicles in Baylis Road
For the latest local news and events direct to your inbox every Monday, you need our weekly email newsletter SE1 Direct.
7,000+ locals read it every week. Can you afford to miss out?
Read the latest issue before signing up