A man was arrested in Arras, France, today after allegedly shooting an automatic weapon on a high-speed train from Amsterdam to Paris, injuring three people. The shooting was reportedly halted when two American passengers overpowered the suspect.

According to CBS News, French media outlets are reporting that the Americans who subdued the shooter were U.S. Marines. A Marines spokesman confirmed to CBS that the shooter was stopped by Americans, but not whether they were Marines.

Two of the victims were seriously injured in the shooting, the BBC reports, and were reported to be British and American. The unnamed suspect is a 26-year-old Moroccan, according to BBC. He reportedly carried an automatic pistol, a knife, and a Kalashnikov rifle.

The third victim was the French actor Jean-Hugues Anglade, who pulled the train’s alarm and was not seriously wounded, according to the Telegraph. It is not clear whether the injured American was one of the apparent Marines who stopped the shooting.

Local police “are not ruling out the possibility of a planned terror attack,” CBS reports.