Train services to Heathrow Airport have been cancelled due to a grass fire near a train track in the London Paddington area.
National Rail said the blaze caused an electricity supply failure, which left all lines between Paddington and the airport blocked.
The Heathrow Express will not run trains in either direction for the remainder of the evening, it said, while Great Western Railway (GWR) also warned of disruption until the end of the day.
Passengers travelling towards Heathrow Airport were told to use the Piccadilly line, or local and London buses.
London Fire Brigade said six fire engines and about 40 crew members were sent to tackle the blaze near Scrubs Lane, North Kensington, where it was called to just after 4.10pm on Saturday.
The 380 passengers left stranded on an Elizabeth Line train were also evacuated by the fire service and Transport for London (TfL).
Photos on social media showed large plumes of smoke rising from the Paddington area.
GWR services to Reading were cancelled because of the incident, while the Elizabeth line was part-suspended.
Heathrow Airport advised passengers to leave extra time for their journeys, adding that the Piccadilly line was also experiencing delays.
TfL said the Elizabeth line was suspended between Paddington and Heathrow terminals four and five, and between Paddington and Reading, and there were severe delays across the entire line. Severe delays also affected the entire Piccadilly line due to an earlier trespasser at Hammersmith, according to the TfL website.
GWR said trains may be cancelled, delayed or terminated at and started back from Reading. However, tickets for Saturday will be valid for travel on Sunday at no extra cost.
