French authorities formally opened a terrorism investigation on Tuesday after a thwarted attack on a high-speed train last week, saying the suspected attacker had watched a radical Islamic video onboard minutes before the violence.

Prosecutor Francois Molins said Tuesday the decision to open an investigation was based on the actions by 26-year-old Moroccan suspect Ayoub El-Khazzani on the train Friday night and information from other European authorities about his travels and apparent links to radical Islam.

Molins said El-Khazzani notably watched the online video on his phone minutes before he walked through the Amsterdam-to-Paris train carrying an assault rifle and other weapons.

Authorities say that they found the suspect’s phone in a bag left in the train. El-Khazzani boarded the train on Friday at a Brussels station.

The gunman was tackled and tied up by a group of three American friends and a British businessman. Another man who tried to stop him — a French-American named Mark Moogalian — remained hospitalized with a gunshot wound.

Now that the formal investigation is opened, investigating magistrates are expected to file numerous charges against El-Khazzani, including an attempted terrorism-related attack.

El-Khazzani was found to have an AKM assault rifle with 270 rounds of ammunition, a 9mm handgun, a box-cutter and a bottle of gasoline, the prosecutor said.

El-Khazzani had travelled through several European countries and had been repeatedly incarcerated in Spain, Molins said. He may have tried to go to Syria.

In questioning, El-Khazzani initially said he had found a bag of weapons the night before in a Brussels park and planned to use them to rob passengers, according to Molins. But his explanation grew less and less lucid, the prosecutor said, and the suspect eventually stopped speaking to investigators at all.

(AP)