One US airman and two other people have been injured in a terror attack on a high-speed French train traveling between Paris and Amsterdam, the Pentagon says.

A 26-year-old Moroccan man, armed with an AK-47 and a knife, opened fire on the train on Friday night before he was subdued by American soldiers.

The gunman was overpowered by the airman, two off-duty US marines and another service member whose branch was unknown, according to an internal Pentagon report obtained by the Military Times.

They wrestled the man to the ground on the Thalys high-speed train, the Voix du Nord regional newspaper said on Friday.

"At this point, we can only confirm that one US military member was injured in the incident; the injury is non life-threatening," said Air Force Lt. Col. David Westover, a spokesman for US European Command. "We will continue to monitor the situation and provide updates as they become available."

The other two people, who were wounded, include a British national and French actor Jean-Hugues Anglade.

The attack is being treated as a criminal investigation and the gunman was taken into custody by the local authorities.

French Interior Minister Bernard Cazeneuve described the Americans "particularly courageous," saying they "showed great bravery in very difficult circumstances".