Army Sgt. Gracie Vaughn and Army Sgt. 1st Class David Cooper were among the people who stopped to aid victims in the tour bus crash Tuesday on the George Washington Parkway. (John McDonnell/The Washington Post)

Army Sgt. 1st Class David Cooper said he was certain about one thing: To free three tourists trapped beneath a shuttle bus tipped on its side, he and three other men would have to lift it.

Minutes earlier on Tuesday, he had been commuting along the George Washington Parkway, the same evening slog he had made between the Pentagon and Fort Belvoir for five years.

Now, he and a band of other commuters were an impromptu rescue team on the scene of a brutal head-on collision involving a shuttle packed with Chinese tourists and a car near Stratford Lane, about a mile northeast of Mount Vernon.

The vehicles collided with such force around 5 p.m. that both skittered off the busy thoroughfare, leaving one person dead and 15 others injured.

The tourist shuttle landed on its side.

During a news conference on June 14, U.S. Park Police Sergeant Anna Rose said more than a dozen good samaritans helped upright a tour bus that collided with a car on George Washington Memorial Parkway near Mount Vernon, killing a bus passenger. (Storyful)

Amid screams of the injured, Cooper pulled over in his car to find a terrible scene: bus passengers trapped inside the shuttle and one tourist pinned and visible beneath it.

In recalling the event Thursday at Fort Belvoir, Cooper said a Coast Guard officer who also stopped pried off an escape hatch on the roof of the shuttle and began helping passengers out.

Cooper said he ran to the back of the bus to throw open the rear door, but to his horror found it bolted.

Cooper returned to the bus hatch, helping the Coast Guard officer who by then had crawled insideto reach passengers and get them off.

But it would take more to free those remaining, Cooper said he eventually realized.

“We have to lift the bus up!” Cooper recalled shouting.

Cooper said he, the Coast Guard officer and two other men counted down and then heaved. The bus slid a couple of feet.

They positioned themselves again.

“This time it seemed like the bus didn’t weigh anything,” Cooper said.

Army Sgt. Gracie Vaughan said she arrived on the scene at that moment as the bus was righted, hearing it land back on its wheels with a thud.

“To me, it was amazing,” Vaughan said of the feat.

When asked how four men were able to lift the bus, the brawny Cooper was at a loss.

“Adrenaline,” he said. “Grace of God. I don’t know.”

Vaughan, also of Fort Belvoir and a human resources specialist, said Thursday that the sight she found on the parkway was reminiscent of those during a tour she served at a combat hospital during the Iraq War.

The rescuers found one woman crushed beneath the bus, another with severe leg damage and a third with extensive injuries.

At the time that Vaughan arrived, the citizen rescue crew had swelled to about 15. Vaughan said some directed traffic around the scene, while others used belts as tourniquets to stanch bleeding. Communication was a barrier because the tourists spoke only Chinese.

Vaughan said the woman who had been pinned under the bus died from her injuries. Her husband was inconsolable nearby.

Vaughan said she pulled a blanket over the woman out of respect.

“When the woman who died woke up this morning, she didn’t realize her last moments would be spent on the side of the road,” Vaughan said. “It makes you realize how fleeting life is.”

Soon, emergency crews arrived on the scene and the band of drivers who had pulled over to help left, resuming their commutes. In all, Cooper estimated, about 10 minutes had elapsed.

A U.S. Park Police spokesman wrote in a message Thursday authorities are still investigating the cause of the crash as the bus carrying 18 passengers and the driver was headed north and the car south. Authorities have not decided whether to press charges and declined to release the name of the tour company or the victim. Two of the 13 injured bus passengers remain in critical condition. The driver and passenger in the car also were among those injured, said Sgt. Anna Rose, the Park Police spokeswoman.

Park Police called the bystanders’ efforts “heroic” and the Chinese Embassy thanked them on Wednesday.

Cooper and Vaughan declined to call themselves heroes on Thursday.

“I just see it as doing what should be done,” Vaughan said.