May 12 (UPI) — A fire at an electrical substation disrupted train service throughout London, including the underground Tube, and forced evacuations at stations on Monday.

At about 2:30 p.m. local time, key parts of the Underground and Overground networks were hit, with Elizabeth, Bakerloo, Jubilee and Northern lines affected, Sky News reported. By Monday night, most services of the 20 lines had been restored.

London Fire Brigade said a cable fault led to an electrical substation fire in west London’s Maida Vale residential neighborhood. The cause is under investigation.

The Jubilee line was suspended on its busiest stretch between London Bridge and Finchley Road, the Independent reported.

Heathrow Airport passengers and staff who normally use the Piccadilly line were affected.

At Piccadilly Circus, one passenger said they were stuck on their train for “quite a long time.”

“Lots of tourists with huge suitcases, plus elderly and disabled people having to climb all the standstill escalators as no lifts were working,” the person said.

Electrical power is handled by National Grid.

“The fault was resolved within seconds and did not interrupt supply from our network,” National Grid posted on X in apologizing for the fault on the transmission network in central London.

On March 20 and 21, a fire at a high-voltage substation in Hayes, West London, disrupted service and caused the temporary closure of Heathrow Airport.

The Tube is the common name for London’s underground rapid transit system in London and outskirts of the city with 250 miles of track. The service opened 1863.

Daily ridership is 3.23 million people.

The Overground is part of Britain’s national rail network.