LONDON — A power cut disrupted rail travel and snarled rush-hour traffic across large chunks of Britain, including London, on Friday, leaving passengers stuck on trains or unable to get home for the weekend.

Power supplier National Grid said two generators failed at the same time around 5 p.m., leading to a drop in the amount of electricity available on the network. It said the system was back to normal about 90 minutes later. It was unclear why the generators failed.

The government's Department for Business Energy and Industrial Strategy said in a statement that "the issue is now resolved and the system has returned to normal."

Electricity companies across the country said hundreds of thousands of customers were affected by the cut, including London's King's Cross station, a major hub for trains between the British capital and the north.

Power failures were reported as far apart as London in southeast England and Cheshire in the northwest. Many people reported that the outage lasted just a few minutes, but the impact on travelers was severe.

Transit operator Transport for London said some traffic lights in the city had been knocked out, and advised drivers to be careful.

National Rail Enquiries, which is run by Britain's train companies, said power problems caused "disruption to a large number of train services."

Rail services across the country were canceled or delayed during the evening rush hour, and commuter trains powered by overhead wires came to a halt mid-journey.

Journalist Stig Abell tweeted: "This power outage has pretty much stopped the rail network. Am on a stationary train in the middle of nowhere." Later he added, "We've just been told to conserve drinking water because 'we might be here for hours.'"

London North Eastern Railway said all services were suspended in and out of King's Cross, one of London's busiest stations. It tweeted: "Customer advice is DO NOT TRAVEL."

"Outside King's Cross Station is absolute mayhem. Nobody knows anything nobody can find an assistant to speak to at this point," frustrated traveler Zoe Hebblethwaite said.

The power failure came as heavy rainstorms drenched the London area, causing flooding at Luton Airport, around 30 miles north of the capital.

The airport said in a statement that the "unprecedented rainfall" had caused "water damage in a number of locations in the terminal" and apologized for the disruption.