The suspect, who French authorities have not identified publicly, was arrested Sunday after apparently shooting himself and calling for an ambulance.
When authorities arrived, a trail of blood from the suspect led them to his car, in which police found heavy weapons, including an AK-47, multiple phones and documents that appeared to show information on potential targets, French prosecutors said. At the suspect’s apartment, police found more weapons and documents that prosecutors said gave clear indications he was planning an attack.
The suspect has also been linked to the apparent murder of a 32-year-old woman, identified as Aurelie Chatelain, who was found Sunday in a car. French Prime Minister Manuel Valls said today Chatelain was a "victim of terrorism."
The suspect is refusing to speak with authorities, prosecutors said.
Prosecutors said the man was already being watched because he had expressed interest in traveling to Syria, but intelligence had not yet found grounds to put him under strict surveillance.
"What could have happened comes as a shock for us all," Valls said. The Prime Minister said two churches were targeted.
"In January, Jews were targeted," he said, referring to the Charlie Hebdo attacks in Paris then. "This time, it was Christians. French Christians... We want, with the Interior Minister, to show our solidarity with Christians who are targeted across the world."