A day ago he was just another tourist on a train. On Saturday, U.S. Airman First Class Spencer Stone was treated for knife wounds in a hospital in France and applauded by world leaders for foiling what officials called an attempted terrorist attack.

Stone was touring Europe with two friends he grew up with in California. The three men in their 20s helped overpower a Kalashnikov-toting suspected Islamist militant on a high speed train heading for Paris from Amsterdam.

Among the other heroes of the nighttime drama was a Frenchman on his way to the toilet who first tried to tackle the assailant as he entered the carriage, and a 62-year-old Briton who still had blood spattered over his shirt as he spoke to journalists on Friday night.

But it may have been Stone, 23, of Lajes Air Base, Azores, who took the biggest risk. Stone's height of at least six feet two inches and Jujitsu martial art and American football background probably helped him, a relative said.

U.S. serviceman Spencer Stone left the Clinique Lille Sud, which specializes in hand injuries, in Lesquin, France, on Saturday. (Reuters) "He was the first one to jump on him, he's the one who got cut up ... none of us are injured but Spencer took a few injuries and he just had no fear," 23-year-old student Anthony Sadler told Reuters.

"That's our friend so once we saw him go we had to go and join him ... We couldn't have just left everybody [to] die like that. It was a crazy situation," said Sadler, a student at Sacramento State University.

Sadler said everything happened very fast as the attacker, armed with an automatic pistol and a box cutter as well as the AK-47 assault rifle, appeared to try to clear his weapon which seemed to be jammed.

Struck by bullet

One French-American passenger was hit by a bullet and was hospitalized for a chest wound. He was in serious but stable condition, authorities said.

"I woke up to basically people ducking and then I was, like, 'Why is everybody ducking?' and then, when I turned round to look, he, the gunman, had just entered the car with the AK and then I was, like: 'This is really happening'," Sadler said.

"We just all ran back there and we tried to do whatever we could to try and beat him up so he didn't shoot anybody. He pulled out a box cutter and cut Spencer a couple of times but beside that we just tried to do whatever we could."

Security was beefed up at Brussels Midi train station after two U.S. soldiers the previous day overpowered an armed man on a French Thalys train travelling from Amsterdam to Paris. (Stephanie Lecocq/EPA) Stone was treated for cuts and left the hospital on Saturday with his left arm bandaged and in a sling. He waved with his right hand to well-wishers and news media.

"Spencer is a very brave person and he has a very good heart, and we're all just so proud of him," his uncle, Tim Eskel, told Reuters by telephone from his home in San Jose, Calif. "All of a sudden your family member is thrust into the national spotlight," Eskel said after U﻿.S. and French presidents Barack Obama and François Hollande commended Stone and his friends.

Conservative Leader Stephen Harper also sent his congratulations.

"The heroic efforts of passengers to confront these terrorists saved innocent people from being murdered," he said in a statement. "This is yet another reminder of the serious threat that terrorism poses around the globe and why it cannot be ignored."

Back from Afghanistan

The third member of Stone's group, 22-year-old National Guardsman Alek Skarlatos, said the vacation was partly to celebrate his return from a tour of duty in Afghanistan.

The men's fathers were thankful things turned out well.

French Interior Minister Bernard Cazeneuve said the gunman may be a Moroccan man identified in 2014 to French police by Spanish intelligence services as having Islamist militant connections. A source familiar with the case told Reuters that fingerprint evidence confirms this. (Regis Duvignau/Reuters) "A guy comes back from Afghanistan and he has to fight a battle on vacation on a train in France," Emanuel Skarlatos said of his son, a college student who works at a Costco retail store as well as serving in the National Guard.

Speaking with Reuters by telephone from his home in Roseburg, Ore., he said Skarlatos and Stone were as close as brothers, having grown up together in Carmichael, Calif.

"They trusted each other where one wouldn't back down if the other was getting his butt kicked," Skarlatos said.

"We're still trying to wrap our heads around it, but we're proud of him," Anthony Sadler's father, also named Anthony, told Reuters by phone. He said the three boys had known each other since middle school.

The elder Sadler, a 57-year-old pastor at Sacramento's Shiloh Baptist Church, said: "We're very, very thankful to God that he was not hurt or killed."

Asked if his son would continue his European trip, Sadler said "No, the trip is over... That's enough. He'll be returning home as soon as possible."

Fingerprint evidence shows that the gunman is a Moroccan known to European authorities as a suspected Islamist militant, according to a source familiar with the case. He is 26 and was under surveillance by Spanish authorities.

Briton Chris Norman, who helped the Americans overpower the gunman, said: "Without Spencer we'd all be dead."

French movie actor Jean-Hugues Anglade, star of "Betty Blue" and "Nikita," who was also on the train, was quoted as saying by BFMTV: "We were stuck in the wrong place with the right people. It's miraculous."