"Crews are currently investigating a fire alert on the Docklands Light Railway at Bank station," London Fire Brigade said in a statement.
A spokesman added that four fire engines were on the scene, a standard response for an incident of this type, which was first reported around 0800 GMT.
A witness said she could smell smoke near Bank station. London's transport authority said it had shut the line between Bank and another station, Shadwell, which is part of the light rail link which connects the Canary Wharf financial district in east London with centre of the city. Meanwhile, travel authority Transport for London said there were no injuries reported following the fire alert.
service between Shadwell and Bank while we respond to a fire alert. To re-plan https://t.co/eyKtMad0UC— DLR (@LondonDLR) August 23, 2017
The BBC reported that the rest of Bank station, which is also on London's underground rail network, was open.