The assailant, who was shot dead Friday, had been radicalized, police said.
Officers stand guard on Friday at the site where police shot dead a knife-wielding man who killed one person and injured at least two others in a park in the suburban city of Villejuif, near Paris.
French prosecutors said a knife attack on Friday that left one man dead and two women injured in a park in the Paris area is being treated as terror-related.
In a statement Saturday, they said investigations over the past few hours revealed that the assailant, who was shot dead by police, had been radicalized and had prepared the attack in Villejuif, in the southern suburbs of Paris.
They said their investigations now justify a probe into “murder and attempted murder in relation to a terrorist undertaking.”
Earlier Saturday, prosecutor Laure Beccuau described the assailant as a 22-year-old man with a long and serious psychiatric history.
Speaking at a news conference, she said he had converted to Islam between May and July 2019 and that he shouted “Allahu akbar” —”God is great” in Arabic — several times during the attack.
She added that investigators are also looking into the assailant’s phone calls and computer equipment. No accomplice has been identified.
Philippe Bugeaud, deputy director of the judicial police, said a letter, details of which were not revealed, and several books about Islam were found in the assailant’s bag, including some about Salafism, widely considered to be a strict interpretation of Sunni Islam.
Two women injured in the attack have been released from the hospital.