French police officers patrol at Gare du Nord train station in Paris, France, Saturday, Aug. 22, 2015.(Photo: Binta, AP)

French President Francois Hollande said Tuesday that his country should be prepared for more attacks after passengers foiled a gunman on a train from Amsterdam to Paris last week.

In a speech, Hollande said Friday's incident "could have degenerated into monstrous carnage without the courage of the passengers," the Associated Press reported.

He said France remains exposed to violent extremism and added that "this aggression is new proof that we should prepare ourselves for other assaults."

Three Americans and a Briton who subdued the gunman on the train were awarded the Legion d'Honneur, France's highest honor, on Monday.

A French citizen who also tackled the gunman but wishes to remain anonymous and Mark Moogalian, a French-American originally from Midlothian, Va, will receive the medal at a later date.

Moogalian, 51, grabbed the attacker's Kalashnikov before the gunman, named as Ayoub El-Khazzani, 26, drew another firearm and shot him, Britain's Telegraph newspaper reported. Moogalian remains in hospital. El-Khazzani, a suspected Islamic extremist, is in police custody.

A teacher and artist who has lived in France for more than 20 years, Moogalian was traveling with his wife Isabella Risacher when the incident happened.

Risacher told Europe-1 radio: "When my husband collapsed, I saw across the seats. He looked at me and he said 'I'm hit, I'm hit.' He thought it was over and he was going to die. The bullet struck him in the back and exited through the neck."

Moogalian 's sister Julia Allen told NBC News on Monday: "You see stuff on the news and you never think it would be our brother. Mark would give anything for anybody. He's just that kind of person."

Hollande presented the Legion d'Honneur to U.S. Air Force Airman 1st Class Spencer Stone, 23; Alek Skarlatos, 22, an Oregon National Guardsman; Anthony Sadler, 23, a Sacramento State University student; and British citizen Chris Norman, 62. The men tackled and subdued the attacker.

The Pentagon said that Stone and Skarlatos are being considered for U.S. military medals, including a possible Purple Heart.

France is on heightened alert after 20 people were killed by Islamic extremists in Paris in January. In June, a man claiming allegiance to Islamic radicals beheaded his employer and set off an explosion at a U.S.-owned gas factory in the southeastern French city of Lyon.

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