(AP) -- A man in a private security uniform stabbed eight people at a Minnesota shopping mall, reportedly mentioning Allah and asking at least one victim if they were Muslim before an off-duty police officer shot and killed him, authorities said.

All nine victims were treated at hospitals for wounds that weren't life-threatening, St. Cloud police Chief Blair Anderson said at a news conference Sunday. Three remained hospitalized. The others were released.

The attack happened at around 8 p.m. Saturday at the Crossroads Center in St. Cloud, a city of about 65,000 people 60 miles (95 kilometers) northwest of Minneapolis.

A man in a security uniform and armed with a knife entered the mall and stabbed people in several locations, including corridors, businesses and common areas, the chief said.

Five minutes after authorities received the first 911 call, Jason Falconer, a part-time officer in the city of Avon, shot and killed the attacker, whose name hasn't been released. Anderson said Falconer fired as the attacker was lunging at him with the knife, and continued to engage him as the attacker got up three times.

"He clearly prevented additional injuries and potential loss of life," Anderson said.

"Officer Falconer was there at the right time and right place," he said.

Anderson earlier said the man reportedly made at least one reference to Allah and asked a victim if they were Muslim before attacking them.

FBI Special Agent-in-Charge Rick Thornton said the attack was being investigated as a possible act of terrorism, but that agents were still digging into the attacker's background and possible motives.

An Islamic State-run news agency, Rasd, claimed Sunday that the attacker was a "soldier of the Islamic State" who had heeded the group's calls for attacks in countries that are part of a U.S.-led anti-IS coalition.

It was not immediately clear if the extremist group had planned the attack or even knew about it beforehand. IS has encouraged so-called "lone wolf" attacks. It has also claimed past attacks that are not believed to have been planned by its central leadership.

Authorities didn't identify the attacker, but Anderson earlier said police had had three previous encounters with him, mostly for minor traffic violations. He said authorities have no reason to believe anyone else was involved in the attack. The FBI is helping with the investigation.

The attack began shortly after an explosion in a crowded New York City neighborhood injured 29 people. A suspicious device was found a few blocks away and safely removed. Hours before that, a pipe bomb exploded in Seaside Park, New Jersey, shortly before thousands of runners were due to participate in a charity 5K race. There was no indication that any of the incidents were linked.

The St. Cloud mall remained on lockdown following the attack, and authorities eventually released those inside. It was closed on Sunday.

Photos and video of the mall taken hours after the incident showed groups of shoppers waiting to be released, including some huddled together near a food court entrance.

Harley and Tama Exsted, of Isle, were in St. Cloud to watch their son play in a college golf tournament and were in the mall when the attack happened.

"All of a sudden I heard pop, pop, pop," Harley Exsted told the St. Cloud Times. "I thought someone tipped over a shelf. All of a sudden these people started running. I just saw everybody running our way."

The couple were unharmed and said they helped another woman who was running from the scene to her car.

Adonis Samuels, 42, of St. Cloud, was outside the mall where his wife Roxanne works as a manager at Clinique at Macy's.

"She called me on the phone and told me she was hiding under the counter with a customer," Samuels said. She later called and said she was safe in a secured area.

Samuels remained outside, watching for her. He said he'd seen her through the glass doors at one point so he knew she was safe.

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Associated Press writer Bassem Mroue in Beirut, Lebanon, and Amy Forliti in Minneapolis contributed to this report.