A report by a news agency linked to the Islamic State claimed on Sunday that a “soldier of the Islamic State” was behind a stabbing attack on Saturday night at a Minnesota shopping mall, an episode that the F.B.I. said it was investigating as a “potential act of terrorism.” Nine people were injured in the attack before an off-duty police officer fatally shot the knife-wielding man, the authorities in St. Cloud said.

The attacker, who was dressed in a security guard uniform, mentioned Allah and asked at least one victim if he was Muslim, the police said. All nine victims were expected to survive.

The Islamic State on Sunday claimed responsibility for the episode, but it was unclear whether the attacker, whom the police have not identified, was in fact acting in the name of the terror group. The Amaq News Agency, which acts as the Islamic State’s newswire, released a bulletin saying the “executor of the stabbing attacks in #Minnesota yesterday was a soldier of the Islamic State.”

The terror group’s bulletin went on to say the attack was a response to the group’s call to “target citizens of countries belonging to the crusader coalition,” a term referring to the United States-led coalition carrying out airstrikes against the group. The language of the bulletin — down to the reference to the perpetrator as a soldier of the Islamic State — mirrors claims of responsibility the group issued for numerous attacks in recent weeks.