A knife-wielding man shouting "allahu akbar" killed his own mother and sister and critically injured another victim during a rampage in Trappes, France, according to officials.

The suspect reportedly stabbed his family members before attacking a female passerby in the street, and was later shot dead by police during a standoff in which he threatened, "Allahu akbar, if you enter I will blast you all."

BFMTV reports the suspect had been on a national terror watchlist since 2016 and was known to promote radical Islamic ideology.

ISIS has claimed responsibility for the attack, proclaiming that the deceased suspect was one of their fighters, SiTE Intelligence Group reports; however, French Interior Minister Gerard Collomb is blaming "significant psychiatric problems" for the man's actions and authorities say his motive is unclear.

"The person who carried out the attack in Trappes, southwest of Paris, was an Islamic State fighter," ISIS declared via its Amaq News Agency. "He carried out the attack in response to calls to target subjects of the countries of the coalition."

Trappes, which lies on the outskirts of the greater Paris metro region, is "known for its social problems linked to poverty, gangs and hardline interpretations of Islam," AFP reports, adding that French security sources have revealed roughly 50 locals are known to have left to join the Islamic State in Iraq and Syria.

(PHOTO: THOMAS SAMSON/AFP/Getty Images)