A famous French actor who was on board the train from Amsterdam to Paris when a gunman opened fire has spoken about the ordeal.

Jean-Hugues Anglade's finger was injured "to the bone" when he shattered the emergency alarm glass. He told Paris-Match magazine that passengers "thought they were going to die" after the first gunshot was heard.

Anglade, whose companion and two children were in the last car, said he heard passengers shouting in English: "He's firing, he’s firing. He has a Kalashnikov."

Criminal and forensic investigators put on protective suits on a platform next to a Thalys train of French national railway operator SNCF at the main train station in Arras, northern France, on August 21, 2015 (PHILIPPE HUGUEN/AFP/Getty Images)

The actor, who has starred in French films such as Betty Blue, went on to allege that train personnel ran down the corridor and took refuge in a work car, locking the door and refusing to answer to passengers.

Anthony Sadler, one of two off-duty US soldiers travelling together, then came into their car and said the gunman had been subdued.

Three Americans in total - one serving in the Air Force, another in the National Guard, and one student - were hailed as heroes for disarming the gunman. A British passenger and a French passenger were also involved in efforts to wrestle the man to the ground.

Alek Skarlatos (left) and Spencer Stone (right) tackled the gunman and subdued him on the train (Alek Skarlatos, Spencer Stone via Facebook)

"We were in a bad spot but with good people," Anglade said. "We were incredibly lucky to have American soldiers with us. I pay homage to their heroic courage and thank them. Without them, we would all be dead."

Le Parisien reported that Thalys director Agnes Ogier had denied Anglade's claims about train staff, claiming that one member of the crew had taken several passengers to safety in the car.

Three people were injured in the attack before the suspect was tackled to the ground by the two soldiers.