President Francois Hollande has bestowed France’s highest honour, the Legion d’honneur on a group of Americans and a Briton who overpowered a Moroccan gunman on a crowded train, saying the whole world admired “their courage and cool composure”.

Anti-terror investigators questioned the alleged attacker, 25-year-old Ayoub El Khazzani, on Monday.

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El Khazzani was interviewed after he allegedly boarded a high-speed train in Brussels bound for Paris on Friday, armed with a Kalashnikov assault rifle, a Luger automatic pistol, ammunition and a box-cutter.

Witnesses said he opened fire, injuring a man before being wrestled to the floor and subdued by three young Americans – off-duty servicemen Alek Skarlatos and Spencer Stone and their student friend Anthony Sadler – and a Briton, 62-year-old business consultant Chris Norman.

“A terrorist decided to commit an attack. He had enough weapons and ammunition to carry out a real carnage, and that’s what he would have done if you hadn’t tackled him at a risk to your own lives,” Mr Hollande said

A French passenger who also tackled the gunman but chose to remain anonymous, and Eric Tanty, an off-duty train driver who happened to be on board and helped restrain Khazzani, will be honoured at a later date.

Mark Moogalian, the man who was shot, and Michel Bruet, a train conductor who warned authorities, will also be awarded medals.

Moogalian, a 51-year-old Franco-American professor, was hospitalised in the northern city of Lille and while his life is not in danger, he remains in intensive care, the hospital said on Monday.

Speaking as he left the ceremony at the Elysee Palace, Mr Norman said it was “a little bit difficult to believe that it’s actually happened”.

“I think that one way or another, we are going to be facing this kind of problem quite a few times in the future, and I would invite you all to think about ‘what would I do in that situation’,” Mr Norman said.

France has been on high alert since extremist attacks in Paris in January left 17 people dead.

Intelligence services in Belgium, France, Germany and Spain had previously flagged Khazzani as an Islamic extremist.

But he was said to have told investigators he was “dumbfounded” by accusations he was intending to carry out a terror attack.

He said he had stumbled upon a weapons stash in a park in Belgium where he sometimes slept rough and decided to use it to rob passengers, according to Sophie David, a lawyer who was temporarily assigned to his case.

Khazzani’s father described his son as a “good boy” who preferred “football and fishing” to politics.

“I have no idea what he was thinking and I have not spoken to him for over a year,” Mohamed El Khazzani told British newspaper The Telegraph.

But Sadler, 23, dismissed suggestions that Khazzani was not trying to kill anyone.

“It doesn’t take eight magazines [of bullets] to rob a train,” he said.