Passengers said it sounded like “a tire blowing out.”

Smoke billowed from the British Air Boeing 777-200 as it taxied into position for takeoff Tuesday at Las Vegas’s McCarran International Airport. Flames shot out from its left engine. A shroud of black smoke seemed to engulf the aircraft.

People watching from the airport were horrified.

“Everyone ran to the windows and people were standing on their chairs, looking out, holding their breath with their hands over their mouths,” Reggie Bügmüncher, who was waiting for another flight, told the Associated Press.

All 159 passengers and 13 crew members aboard Flight 2276 headed for London’s Gatwick Airport were led from the plane. At least 20 were taken to a hospital with minor injuries, according to NBC News. All have since been released.

National Transportation Safety Board spokesman Eric Weiss told The Washington Post on Wednesday afternoon that the agency was sending systems specialists and a fire expert to investigate the incident. Initial reports from the Federal Aviation Administration stated that the issue came from the left engine as the plane was accelerating on the runway, but Weiss said NTSB investigators will determine the cause.

General Electric, the engine’s manufacturer, said in a statement “we are not aware of any operational issues that would hazard the continued safe flight of aircraft powered by these engines,” but that it would send technical representatives to help with the investigation, according to Agence France-Presse.

In any case, the incident could have meant disaster had the London-bound plane’s crew and passengers not made a hasty and efficient exit down the inflatable evacuation chutes and had firefighters been slower in dousing the flames.

As it turned out, the fire and smoke did not penetrate the cabin, though witnesses told NBC News the heat was so intense it melted windows on the plane. Fire officials initially told the Associated Press 14 people suffered minor injuries from sliding down the chutes after the fire broke out Tuesday afternoon.

By all accounts, effective management prevented the incident from turning into a tragedy. One passenger, Karen Bravo, 60, told the Las Vegas Review Journal, the evacuation could serve as “a training video. Everybody did their job.”

Here’s one version of how it happened, tweeted by passenger Jacob Steinberg, a writer for the Guardian.

Steinberg said he was asleep as the plane was taking off. Suddenly it “came to a crashing halt.” There was a “smell of smoke,” and passengers were told to stay seated before the pilot ordered the evacuation.

“They opened the back door and [the slide] went down and smoke started coming” in the plane, “followed by a mad dash to the front. A lot of panic,” he tweeted.

“Emergency evacuation,” the pilot said, passenger Lynne Alexander told BBC News. “Off plane now.”

The plane’s captain, identified by the Guardian as Chris Henkey, 63, called for emergency services: “Speedbird Mayday Mayday. Speedbird 2276 request fire services. Speedbird 2276 heavy. We are evacuating on the runway. We have a fire, repeat, we are evacuating,” according to BBC News.

“Pretty scary stuff,” passenger Jay Jennings, who was on the plane and was one of the ones injured, told CNN. He said that as the plane was preparing to take off, he heard a thud and lifted the shade on his window. “Just saw flames on the engine,” he said. After a minute of standing still, the captain announced over the intercom that there was an emergency and instructed the passengers to evacuate.

Jennings told CNN that after the emergency doors opened, smoke flowed into the cabin.

“The plane’s on fire! We have to get off this plane!” Letha Dunn told NBC News some shouted.

“People were pushing and shoving and screaming. There was panic, but then the chute was deployed and down I went,” Alexander told BBC News. “We ran far from the plane as the fire crew arrived and doused the engine.”

The flight was scheduled to depart at 4:04 p.m. but was still taxiing on the runway when the crew reported the fire at 4:13 p.m., Rosemary Vassiladis, the airport’s director of aviation told the Review Journal. The Clark County Fire Department arrived at 4:14 and the fire was extinguished by 4:18, she said.

Passengers who were not hospitalized were put up at a local hotel.

Steinberg told the Guardian that passengers applauded Henkey, who has been a pilot for 42 years.

“He was speaking to a few passengers later and all the color had drained from his face,” Steinberg said. “We shook his hand and thanked him. There were not enough words in the world for us to express our gratitude.”

British Airways and Boeing have since apologized to passengers.

“Our crew evacuated the aircraft safely and the fire was quickly extinguished by the emergency services at the airport,” British Airways said in a statement. “A small number of customers and our crew have been taken to hospital. All customers have been provided with hotel accommodation, and our colleagues are helping them with anything further they require.”

Passengers on other flights and in the airport captured the scene.

This photo was taken from the view of a plane window. (Eric Hays via AP)

This photo was taken from the view of a plane window. (David Somers via AP)

The British Airways plane stands on the runway surrounded by emergency vehicles. (L.E. Baskow/AFP/Getty Images)

Firefighters enter the plane. (John Locher/AP)

(Steve Marcus/Reuters)

Correction: An earlier version of this story incorrectly stated that General Electric manufactured the aircraft. It manufactured the engine. The story has been updated.