A gunman overpowered by passengers during a shooting on a high-speed train in France on Friday is known to European authorities as a suspected Islamist militant if the identity he has given is correct, France's interior minister said on Saturday.
He has been identified as dangerous by foreign security services and has been under police surveillance, a French source with knowledge of the case said.
Two people were wounded in the struggle to subdue the Kalashnikov-toting attacker aboard the high-speed train from Amsterdam to Paris on Friday. Two US servicemen, one of whom suffered knife wounds, were among the passengers who stopped the gunman.
Cazeneuve said the man's identity was not confirmed, but if he was telling the truth "he is a 26-year-old man of Moroccan nationality identified by the Spanish authorities to French intelligence services in February 2014 because of his connections to the radical Islamist movement".
The man Spanish authorities had under surveillance left Spain for France in 2014, travelled to Syria, and then back to France, a Spanish counter-terrorism source said on Saturday.
In Spain, he lived in the southern port of Algeciras and appeared to have stayed in the country for about a year, the source said.
Cazeneuve did not mention any visit to Syria or France, only naming Spain and Belgium as the suspected militant's places of residence, this year and last. He said inquiries in collaboration with other European authorities "should establish precisely the activities and travels of this terrorist".
French newspaper Le Voix du Nord said the suspect may have had connections to a group involved in a suspected Islamist shooting in Belgium in January. The Belgian government confirmed an inquiry but would not comment further.
French authorities have been on high alert since January, when 17 people were killed in shootings by Islamist militants in and around Paris.
Kalashnikov, pistol, and box cutter
The attacker was armed with a Kalashnikov assault rifle and an automatic pistol, both with accompanying ammunition clips. He also had a box cutter knife. Cazeneuve said the struggle started when a Frenchman on his way to the toilet tried to stop the man entering a carriage.
The wounded US serviceman, airman Spencer Stone of Lajes Air Base, Azores, was expected to be treated at a specialist hospital for people with hand injuries in the northern French city of Lille.
Among the other passengers who helped stop the attacker were Stone's friends: National Guardsman Alek Skarlatos and another American, student Anthony Sadler. Skarlatos had returned last month from a tour of duty in Afghanistan and the three were on holiday together in Europe.
Cazeneuve said the other wounded person was of Franco-American nationality, hit by a bullet while seated. Authorities said on Friday night that a French actor had also been hurt.
"We were stuck in the wrong place with the right people," the actor, Jean-Hugues Anglade, was quoted as saying on BFMTV. "It's miraculous."
President Barack Obama hailed the passengers as heroes: "It is clear that their heroic actions may have prevented a far worse tragedy."
President Francois Hollande is due to thank them in person in the coming days.
The gunman was transferred on Saturday to the Paris region from Arras in northern France where the incident took place. Cazeneuve said under the terms of his arrest the man can be held for four days without being charged.
The shooting took place on a Thalys high-speed train. The Franco-Belgian state transport group runs international trains linking France, Belgium, the Netherlands and Germany.
All four countries are part of the Schengen area through which people travel without the need for passports and security check-ins. Experts have long said the trains are a potential target for attacks.