One of London's busiest Tube lines was brought to a standstill as engineers scrambled to fix a signalling problem.
The Central line was suspended completely between Marble Arch and Leytonstone from about 11pm on Thursday.
Services on the busy line were halted while emergency engineering work was carried out to fix a signal failure at Liverpool Street station.
The line, which calls at busy stops such as Oxford Street, Holborn and Bank, has since been reopened but customers still face severe delays.
The same signalling fault at Liverpool Street, and another at Earls Court, also sparked severe delays for Londoners travelling to work on the Central and District lines.
Services on the Overground were suspended between Highbury & Islington and West Croydon, Clapham Junction, Crystal Palace and New Cross.
TfL apologised to customers for the delays.
Speaking before Central line services resumed, Nigel Holness, TfL’s director of network operations for London Underground, said: “We apologise to customers whose journeys are disrupted as a result of a signal failure at Liverpool Street this morning.
“Our engineers are working hard to repair the fault as quickly as possible in order to resume a normal service.”
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After services on the Central line resumed, passengers were still being urged to seek alternative routes as severe delays to services continued.
TfL wrote on Twitter: “Train services resume with severe delays to all destinations following emergency engineering work at Liverpool Street. Please continue to use alternative routes where possible.”
It came amid industrial action as members of the RMT union staged 24-hour walk-outs on Monday and Wednesday, with plans for further strikes on Friday.
