(CNN) The man who stabbed nine people at a Minnesota mall Saturday before being shot dead by an off-duty police officer was a "soldier of the Islamic state," according to an ISIS-linked news agency.

The statement posted online Sunday by the Amaq agency follows a pattern of ISIS-related media claiming responsibility for what appear to be the acts of individuals across Europe in the past few months.

CNN cannot independently confirm this latest claim.

"We still don't have anything substantive that would suggest anything more than what we know already, which is this was a lone attacker," St. Cloud Police Chief William Blair Anderson told CNN's Jake Tapper Sunday. "And right now, we're trying to get to the bottom of his motivations."

The FBI is calling the attack "a potential act of terrorism."

Community leaders fear anti-Muslim backlash, call for unity

In response to local reports identifying the attacker as being of Somali descent, members of the Muslim and Somali communities held a news conference Sunday expressing their grief for the victims and calling for unity.

"We are also concerned about the potential backlash," said Jaylani Hussein, executive director of the Council on American-Islamic Relations (CAIR) chapter in Minnesota. "We understand in St. Cloud there is more anti-Muslim organizing and we hope they do not use this incident to divide ... our community."

Ahmed Said, executive director of the Somali American Relations Council, had previously disclosed that it was unclear if religion motivated the attack, "but we know he is Somali," the Minneapolis StarTribune quoted him as saying. Authorities have yet to confirm the attacker's ethnicity. CNN was also unable to confirm if he was Somali.

St. Cloud is home to one of Minnesota's larger immigrant Muslim communities and tensions with some members in the larger community have spiked at times, the StarTribune reported . The Minneapolis newspaper and the St. Cloud Times identified the attacker as a member of the Somali community.

In 2014, there was damage to mosques in St. Cloud and in 2013 the Muslim community in the city withdrew a bid to build a larger mosque because of tensions, the StarTribune reported.

Speaking at Sunday's news conference, Mohamoud Mohamed, a spokesman for the Central Minnesota Islamic Center in St. Cloud, emphasized that the central Minnesota Muslim community has no relationship with ISIS or any other "Islamic terrorist group."

"We are the victims of those terrorist groups," he said. "Islam is peace... I pray for the victims."

The state was at the center of a federal investigation into the recruitment of fighters for ISIS . Nine Somali-Minnesotans were convicted at trial or pleaded guilty in a plot to travel to Syria to join ISIS. In years back, several dozen male residents left to join Al-Shabaab , a terrorist group working to turn Somalia into an Islamist state.

"What's remarkable about this case was that nothing stopped these defendants from plotting their goal," said US Attorney Andrew M. Luger of the District of Minnesota in announcing federal charges against the men.

"They were not confused young men. They were not easily influenced. These are focused men who are intent on joining a terrorist organization by any means possible."

But on Saturday, a Somali-American mother said she waited fearfully outside the mall Saturday, just like other citizens of the central Minnesota city, because her son was inside during the attack.

"This has been a dark day; it is a day we will never forget," said Lul Hersi. "Let us unite as one Minnesota... Please let's spread love instead of hate. ISIS does not represent us. It does not represent Islam, and it does not represent Somalis."

The attack at the mall

Police and witnesses said the man, wearing a private security company uniform, entered Crossroads Mall on Saturday night around 8 p.m. CT, made a reference to Allah and asked at least one person if they were Muslim before he attacked.

St. Cloud Mayor Dave Kleis said three people remain hospitalized, including one person who is in a life-threatening condition.

Ashley Bayne, an employee of JCPenney at the mall, was visiting a coworker at the time of the incident.

"All of sudden chaos just broke out," she told CNN's Nick Valencia on Sunday. "There was a bunch of people running into the JCPenney mall entrance, and they were just screaming that someone was going around the mall stabbing people, and that there was blood everywhere. It was just honestly a really scary experience."

Bayne said she ran out to the parking lot and took off in her car.

The stabbings occurred in multiple locations inside the mall, including the common area and in several stores. The mall has security teams on site but they are not armed.

Police knew attacker

While the attacker was not identified, authorities said he'd had three previous encounters with police.

Anderson said most of the encounters were for minor traffic violations. None resulted in an arrest.

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Anderson declined to provide further details or say whether the attacker was a resident of St. Cloud. He said he is not ready to describe the stabbings as a terrorist attack until details such as a motive are established.

He's "clearly a hero"

The mayor and police chief praised Jason Falconer, an off-duty police officer from nearby Avon, for killing the suspect as the assailant threatened other people in the mall.

Falconer is a part-time officer for Avon and a former police chief of Albany, Minnesota, the officials said at a news conference Sunday afternoon. Both officials said they had viewed a surveillance tape from a Macy's store which revealed details of the confrontation.

"Officer Falconer was there at the right time at the right place," Mayor Kleis said.

"His heroic actions are exemplary of having witnessed what he did as the suspect was lunging at him with a knife. Not only did he fire, the suspect went down, came back up on three different occasions. He protected others from being injured and potentially loss of life. Clearly, a hero."

City changed forever

The police chief said two search warrants were executed at an address in St. Cloud, and the suspect's vehicle has been impounded.

Chief Anderson said the attack had changed the city forever. St. Cloud is about 65 miles northwest of Minneapolis and has a population of 67,000.

"Whenever something as awful as this happens, it's hard for things to be the same as they were," Anderson said.

The mall will reopen Monday.

"Honestly, last night once everything had happened it still felt unreal, it didn't seem like something that would happen at our mall," said Bayne, the JCPenney employee. "I've been a little shaky ... kind of been crying about it a little bit. But it's definitely something you think about after it happens ... It's really scary to think about and I'm ... just thankful to be alive."

Other attacks

The mall stabbing was one of several incidents reported nationwide Saturday.

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