Becky Davies, 41, traveled to Las Vegas from Doncaster, a town in northern England, to celebrate her 20th wedding anniversary with her husband. But now, the couple is stuck in the city and unable to return home to their kids.

"It was a special trip for us. It’s just a shame it’s all gone so wrong at the end," she said.

Davies, who was due to fly back to London on a Virgin Atlantic flight at 9:45 p.m. PT (6:45 a.m. ET) said she was standing at the gates when a staff member from the airline told the couple they would be given overnight accommodation at a nearby hotel after all flights were suspended due to Heathrow's shutdown.

But when they got to the hotel, Davies said the room they had been given was "just awful," adding, "Someone had been staying in there, and nobody came to make the room up once they checked out. There was rubbish everywhere."

The couple, who have four children, three at home, eventually returned to the airport to find other accommodation, but Davies said she was eager to return home. "My youngest is only 8, so she was so excited to see us come home," she added.

London's Metropolitan Police's counterterrorism unit is investigating the cause of the electricity substation fire that brought Heathrow to a standstill last night and into today, but sabotage was not suspected.

A Met spokesperson told NBC News that there was no indication of any foul play, but added that it had not yet ruled out the possibility.

Planes sit on the tarmac as passengers face an agonizing wait for news with their luggage outside Heathrow Airport in London today.

Chez Khan spent the past week away from his family at a work conference in Las Vegas, but now, the 47-year-old client services director from London finds himself stranded in a hotel that's a 45-minute drive from the airport.

"We were just in the dark for about three to four hours" after the power outage at Heathrow, Khan told NBC News over the phone.

When his airline carrier, Virgin Atlantic, directed a group of passengers including Khan to a Holiday Inn near the airport, the hotel staff told them that no one had contacted them and that they had no rooms available.

"We were then sent back to the airport, and no staff were available to help," he said, adding, "So we were literally left stranded in Vegas."

Khan, who eventually found other accommodation through work, said that he has since been waiting for further updates about when he can get a new flight home.

"The biggest impact for me personally is missing the kids," he said, adding, “That I was away from home for a week was already a challenge."

Trains on London’s typically busy Elizabeth line, which runs on an east–west axis across the British capital, were unusually quiet this morning, as passengers traveling to and from Heathrow were absent.

The eastbound train is normally filled with weary looking travelers headed into the city and out east, their luggage often taking up large swaths of the floor space.

But this morning, it was eerily quiet until passengers traveling from the busy Paddington Station began to file in.

The Elizabeth line is named after the late Queen Elizabeth II, who formally opened it in May 2022. Since then, it’s become a popular means of travel to Heathrow, providing speedy service to the airport.

She was supposed to run two major sessions at an education conference in Chicago, but Halleli Pinson, 51, a professor of sociology of education at Israel’s Ben Gurion University, is stuck in London.

“I’m not only missing my own talk, I’m missing other responsibilities that I have,” Pinson told NBC News today in a telephone call. She added that the earliest British Airways could fly her to Chicago was Monday, but by then it would be too late.

Pinson's sister, Shira Pinson, is a multimedia producer for NBC News who lives in London and said she will be able to "put up or put up with her sister." But Halleli said she was “frustrated” with British Airways because they had not made “any efforts to put me on a different airline or a different flight.”

Delta, American Airlines, and Jet Blue have issued travel waivers for passengers affected by the flight disruptions at Heathrow.

Delta Air Lines said it would waive the fare difference while reissuing tickets to passengers flying between March 21 and March 23 to and from the airport by no later than March 26.

Those unable to reschedule their flights within these guidelines “may cancel their reservation and apply any unused value of the ticket toward the purchase of a new ticket for one year from the original ticket issuance,” it said in a statement.

The London Fire Brigade said that the fire that left Heathrow in the dark and unable to serve passengers involved an electrical substation with 25,000 liters of cooling oil that was on fire.

Jonathan Smith, deputy commissioner with the fire brigade, told a news conference this morning that the fire began at 8:23 p.m. last night (4:23 p.m. ET) and it took 10 fire engines and 70 personnel to get it under control.

Firefighters evacuated 29 people from surrounding homes, and 150 more in an exclusion zone were taken to a rest center.

"Our firefighters worked tirelessly in challenging and very hazardous conditions under control as swiftly as possible," he said, adding that the fire is now 90% extinguished.

Smith would not comment on the cause of the fire.

Taylor Collier-Brown is stranded in Geneva with her hockey team after their flight to Heathrow was canceled following a skiing trip to Morzine in the French Alps.

She's hoping there's a way for the British team to get back to London before a match tomorrow.

“Eleven hockey girls with a match tomorrow can’t make it back — the whole team is in Geneva,” she said.

The team is asking if anyone has a jet to get it home before the big game.