The three American friends who helped foil what could have been a mass shooting on a packed high-speed train bound for Paris started their journey in a different car, they said Sunday, underlining how easily their triumph could have been a tragedy.

When they got on the train Friday in Amsterdam, they could not find their first-class seats, so they sat elsewhere, said Anthony Sadler, one of the three vacationing childhood friends.

They have been lauded as heroes by President Obama. French President François Hollande on Monday awarded them the Legion of Honor, France’s highest decoration. But on Sunday, amid gilding and tapestries in the U.S. ambassador’s residence in Paris, they stayed humble. Only chance led them to change their seats, one said — not heroism.

“We decided to get up because the WiFi wasn’t so good on that car,” said Sadler, 23, a college student. “We were like, ‘We have a ticket to first class. We might as well go sit in first class.’ ”

About half an hour after the train pulled away from Amsterdam, they switched to the car where the shooter soon opened fire, he said.

At a news conference in Paris, Spencer Stone, Anthony Sadler and Alek Skarlatos explained how they put down the gunman in the France train attack. (The Washington Post)

Along with two other men, they tackled, then disarmed, a suspected Islamist militant who packed two guns, a knife and nine clips of ammunition into his rucksack.

“He seemed like he was ready to fight to the end. So were we,” said Airman 1st Class Spencer Stone, his left arm in a sling, his right eye bloodshot and watering.

The three men — friends since middle school in California — appeared together in public on Sunday for the first time since they overpowered and then tied up the shooter. Stone’s hand was heavily bandaged after an operation to reattach his thumb, which was nearly severed during the attack. All three looked exhausted and sported days-old beards.

But they displayed some of the instinctive camaraderie that on the train led them to leap from their seats in seconds to take on the shooter as a team. They finished one another’s sentences and silently communicated with each other with cocked eyebrows and tiny facial expressions.

Stone, giving his account for the first time on Sunday, said that he had simply had one idea in his mind as he sprinted to disarm the assailant: “Survival.”

He was in “the middle of a deep sleep” when he heard the initial scuffle between the shooter and the French citizen who was the first to stumble on him, he said. But then his friend, Oregon Army National Guard Spec. Alek Skarlatos, 22 and recently returned from a deployment in Afghanistan, “just hit me on the shoulder and said ‘Go,’ ” Stone said.

One of the Americans who overpowered an attacker on a high-speed train travelling between Amsterdam and Paris managed to film the scenes in the carriage moments after the suspect was subdued. (AP)

There was no time to plan, they said, no time even to think.

“We just kind of acted. There wasn’t much thinking going on,” Skarlatos said. “At least on my end.”

Stone said that after the suspect was tied up, he saw that another passenger had been severely wounded by a bullet during the attack and was “squirting blood” from his neck. Stone said he barely felt any of his own injuries, so he focused on saving the other victim’s life. He stuck two of his fingers into the passenger’s wound to hold an artery closed until paramedics showed up.

But Skarlatos said the tragedy had also been averted because of the shooter’s incompetence. Both his guns, an AK-47 and a Luger pistol, appeared to have jammed, he said.

“He clearly had no firearms training whatsoever,” Skarlatos said. “If he had known what he was doing, or even just got lucky and did the right thing, he would have been able to operate through all eight of those magazines.

“We probably wouldn’t be here today, along with a lot of other people.”

On Monday, they will be given the Legion of Honor by Hollande in the ornate Elysee Palace, along with a Briton who also helped subdue the shooter.

Now sharp criticism is being leveled against Europe’s security preparedness, because the suspect had been flagged by counterterrorism authorities in three countries as a potential risk. He was allowed onto the high-speed train — a favorite of government officials, businesspeople and tourists — without any security checks. French and Belgian security officials had the man on their radar for more than a year, and Spanish authorities had been in contact with him since at least 2010, when he was picked up for selling hashish.

Belgian Prime Minister Charles Michel accused him of engaging in terrorism.

French counterterrorism authorities continued to interrogate the man Sunday, identified by security officials as Ayoub el-Khazzani, a Moroccan two weeks short of his 26th birthday. He painted himself as a loner in initial police interrogations in the hours after the attack, according to the lawyer who represented him there, Sophie David. Khazzani said he had left school around the age of 12. He said he had cut off contact with his family, although he did not explain why, David said.

Spanish authorities say Khazzani crossed their path several times starting in 2010 for selling drugs but that he never spent time in prison. But they noticed his visits to a mosque known for its violent messages.

“He has been on our radar for a long time. We saw that he was radicalized,” said a Spanish security official, speaking on the condition of anonymity to discuss internal investigation documents. “We have very many of these kind of profiles: people of concern, but not to the extent that we could say they would do terrorism attacks.”

Some posts on Khazzani’s Facebook page, which has been taken down, show fleeting glimpses of ultraconservative Islam mixed with angry political ideology. In November, Khazzani reposted a video from an ultraconservative Salafist imam. In January, days after terrorist attacks in Paris on the Charlie Hebdo satirical newsweekly and a kosher supermarket killed 20 people, including the three shooters, he reposted an image that said in Arabic: “France is not a terrorist gang or a fundamentalist group. It is a civilization based on terrorism.

“The Jewish and Christian infidels are the source of terrorism and radicalism, and they are the ones that nourish it and stand for it,” the image read, according to screen captures of the profile taken before it was removed. The image referred to Algeria’s bloody war for independence from France in the mid-20th century.

But Khazzani denied any links to terrorism. He said he had found his trove of arms in a Brussels park where he had been sleeping on benches. It was enough firepower to kill dozens in a matter of minutes. But he said that what happened on the train was simply a botched robbery, said David, the lawyer.

She said Khazzani was slight and weak, as though he had been homeless for some time. He denied any connection to Islamist militancy, she said, and maintained that he wasn’t religious.

“When we asked about it, he laughed and said ‘No,’ ” David said.

After he left Spain in early 2014, Khazzani went to France but may have soon traveled to Belgium. In the past six months, he traveled throughout Western Europe, he told investigators, to Austria, Andorra, Belgium and Cologne, Germany.

The three Americans may have been humble, but Sadler didn’t stop himself from playing investigator Sunday. When asked whether the friends believed the suspect’s story, Sadler said, “It doesn’t take eight magazines to rob a train.”

Pauline Bock in Paris, Souad Mekhennet in London and Heba Habib in Cairo contributed to this report.