There is currently no service on the Bakerloo Line between between Harrow & Wealdstone and Queens Park while a signal failure at Wembley Central is being fixed.
There are minor delays on the rest of the line towards Elephant & Castle.
The Overland service is also affected with no service between Euston and Harrow & Wealdstone.
In a separate incident Euston station has been evacuated following a fire on the track.
There are minor delays between Willesden junction and Clapham Junction due to damaged track side equipment.
Transport for London said tickets will be accepted on London buses via any reasonable route.
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