A man has died while working on a moving walkway at Waterloo station.
Paramedics were unable to save the worker, who has yet to be identified, and he was pronounced dead shortly after 02:20 BST.
British Transport Police officers are investigating the death, which is being treated as unexplained.
Vernon Everitt, London Underground’s managing director, expressed “deepest condolences” to the man’s family from the rail network.
“We are also very conscious of the impact this sort of incident has on first responders and station staff, and a full support network has been stood up,” he added.
Passengers were advised they would be unable to change lines because of a fault with one of the Tube station’s two travelators.
A one-way system has been implemented at the station for Wednesday morning.
The man’s next of kin has not yet been contacted.