LILLE, France (AFP) - A British man who helped subdue a gunman who opened fire on a high-speed train from Amsterdam to Paris said Saturday he thought the man's rifle may have jammed.

Chris Norman, a 62-year-old business consultant advising African entrepreneurs, was returning home to the south of France when he heard shots fired behind him on Friday evening aboard the train.

"My first reaction was to hide but I heard an American shouting to get him, and decided we had more chance of surviving if we worked together," he told reporters.

"My thought was I'm probably going to die anyway. I'd rather die being active, trying to get him down than simply sit in the corner and be shot."

He was said he was scared "initially" but that "once you start moving, you're not afraid any more."

The gunman, identified as a 25-year-old Moroccan, was overpowered by three Americans - including two off-duty servicemen - as well as Norman.

No one was killed in the attack, and Norman said he thought the man's Kalashnikov rifle may have malfunctioned.

"The attacker started to get his arsenal out as he went from carriage 13 to 12. I don't know why he didn't manage to fire but I think it's because his weapon jammed," he said.

"I don't feel like a hero. If there's a hero it's Alexander Skarlatos and Spencer (Stone)," said Norman, referring to the two US servicemen who made the first move on the gunman.

"If it wasn't for Spencer, I think we would all be dead."

He said Stone had taken the gunman in a chokehold and Norman took his right arm to stop him reaching his gun.

With the man floored, Skarlatos left to search for more terrorists, while Norman helped tie up the attacker with his tie.

Stone then went to help an injured man, though he was suffering several injuries to his neck and thumb.

"He said he was a medic and he's the one who went to stop the man's bleeding," said Norman.

He added the episode only started to sink in when "I tired to shut my eyes last night," adding that he did not sleep at all.

He said he had spoken to his family, who were proud of him, and was keen to rejoin his wife and grandchildren in the south of France.

British Prime Minister David Cameron had earlier saluted Norman's "extraordinary courage".

"The bravery of Mr Norman and the other passengers helped to prevent a terrible incident," Cameron said in a statement.