UPDATE 4:55 p.m. EDT: French President Francois Hollande expressed his gratitude to President Obama for the actions of the three Americans in thwarting the terrorist attack, a White House readout said. The two leaders agreed the three,along with a French and a British passenger, demonstrated "remarkable bravery and acted without regard for their own safety."

UPDATE, 2:12 p.m. EDT: President Obama also thanked the group of Americans by phone, according to a White House official, expressing his "gratitude to these three individuals for their heroic actions."

Original story below.

French President Francois Hollande has thanked three Americans for their roles in foiling a potential massacre on board a high-speed train on Friday. While en route from Amsterdam to Paris, the group helped subdue a heavily-armed, 26-year -old Moroccan man moments after he opened fire.

The gunman, whose identity has yet to be released, boarded the train in Brussels. After a passenger encountered him by the bathroom, a struggle ensued, and a gun was fired, according to French Interior Minister Bernard Cazeneuve. Shortly thereafter, two Americans intervened -- Air Force serviceman Spencer Stone and Alek Skarlatos of the National Guard -- disarming and subduing the assailant.

“Spencer got to the guy first and grabbed the guy by the neck,” Skarlatos told Sky News. “I grabbed the handgun, got that away from the guy and threw it. Then I grabbed the AK-47, which was at his feet, and started muzzle-bumping him in the head with it.

“Everybody just started beating the guy while Spencer held the chokehold until he went unconscious,” he continued.

They were aided by American college student Anthony Sadler and British passenger Chris Norman. After the failed attack, the train stopped in the northern French city of Arras, where the suspect was arrested and taken into custody.

Hollande thanked the men by telephone, Cazeneuve said at a press conference. The interior minister also praised their “great bravery in trying circumstances.” On Saturday, Hollande tweeted that he would host the “Americans and French” who helped subdue the gunman and show them “the gratitude of France.”

Three of the four passengers who helped take down the gunman were awarded medals by the city of Arras. In a tweet, the mayor praised the “American heroes.”

RTX1P662 French authorities look for clues on the train platform in Arras, where the gunman was arrested. Photo: Reuters/Pascal Rossignol

Air Force member Spencer Stone remains hospitalized for injuries suffered during the tussle. He was "slashed multiple times" with a knife by the attacker, Anthony Sadler told CNN. Two others were injured in the attack.

Spanish press has reported the suspect was under watch by the country's anti-terrorist authorities and had recently traveled to Syria. The train was carrying 554 passengers.