(CNN) Dahir Adan had been in a "joyful" and "happy" mood on Saturday before he went to a St. Cloud, Minnesota, mall to buy a phone, a community leader told CNN on Monday.

Adan, a private security firm employee with a good reputation in St. Cloud's Somali community, was intent on purchasing the newly released iPhone 7, according to Haji Yussuf, a local Somali community leader who has been in contact with the man's family.

Adan, 22, is suspected of storming the mall and stabbing 10 people Saturday night before he was shot dead by an off-duty police officer.

Earlier, two Somali community leaders in contact with the man's family told CNN that Adan had been acting strangely before the incident.

Details about Adan and the incident began to emerge Monday as authorities worked to piece together the suspect's background and pinpoint his motive, St. Cloud Police Chief William Blair Anderson told reporters.

"We are trying to find everything," Anderson said. "I want to know everything about this man, from the day he was born until last Saturday."

Federal law enforcement sources and Somali community leaders identified Adan on Monday. An ISIS-linked news agency praised him as a "soldier of the Islamic state."

CNN hasn't independently verified the claim, and on Monday, authorities maintained that the suspect appeared to have acted alone.

"We haven't uncovered anything that would suggest this was anything but a lone attacker at this point," Anderson told reporters.

The FBI is calling the attack "a potential act of terrorism." But no evidence has been found tying the suspect directly to terror groups, the police chief said.

A portrait of the stabbing suspect

Adan had a stellar reputation in St. Cloud's close-knit Somali community, said Yussuf, who is a director at #unitedcloud , a group that works to resolve tensions in St. Cloud.

Yussuf called him a "very exceptional young man" who loved his family and respected his community. He was an "exceptional student" and "very smart," he said.

"We're all trying to find answers as to what happened," Yussuf said. "The family is very frustrated about this, very sad."

Yussuf said family members want to see the footage of the incident, in which the suspect was said to have lunged at people before he was shot.

Yussuf praised law enforcement, saying it is doing an "amazing job" trying to get to the bottom of the case.

But he finds any link between ISIS and Adan hard to believe and at this point, he said, there is no connection.

"The idea that people like ISIS will claim this responsibility for us is ridiculous," he said.

JUST WATCHED ISIS claims 'soldier' who stabbed victims at mall Replay More Videos ... MUST WATCH ISIS claims 'soldier' who stabbed victims at mall 00:47

Community leaders fear anti-Muslim backlash

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As news of the incident emerged, local newspapers in Minnesota, including the Minneapolis Star Tribune and St. Cloud Times, identified the attacker as a member of the Somali community from the central part of the state.

St. Cloud, a city of 67,000 about 65 miles northwest of Minneapolis, is home to one of Minnesota's larger immigrant Muslim communities, and the incident has rattled people there.

In recent years, the Muslim community has faced conflicts with other Minnesota residents, including vandalism to mosques and opposition to at least one new Islamic house of worship, according to the Star Tribune

Federal investigators have tracked the recruitment of potential ISIS fighters in Minnesota. Since 2014, nine Somali-Americans from that state were either convicted at trial or pleaded guilty in a plot to join ISIS by traveling to Syria. Before that, dozens of male Minnesota residents had left to join Al-Shabaab, a terrorist group working to turn Somalia into an Islamist state.

Yussuf noted that the mall incident occurred amid a contentious US presidential election, with its debates about restricting the flow of immigrants, and Somalis worry it could threaten the amity forged between them and their neighbors.

"It's affected all of our community," he said. "Nationally, there is the issue of immigrants and the presidential elections and people are saying things about immigrants and refugees -- about Mexicans, about Muslims. For 30 years people have been building bridges in our community and we are all afraid that this will disappear because of this one incident."

Muslim and Christian clergy and community leaders gathered on Monday afternoon. They expressed unity and community spirit with one Muslim leader calling ISIS un-Islamic and better called a "Luciferian cult."

Jaylani Hussein, executive director for the Council of American-Islamic Relations Minnesota said leaders are starting a hashtag for social media #stcloudtogether.

"This community, after this horrific tragedy, will move forward," he said.

The attack at the mall

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

Ashley Bayne, an employee of J.C. Penney at the mall, was visiting a co-worker at the time of the incident. When the stabbings began, Bayne ran out to the parking lot and took off in her car, crying and shaking in the aftermath of an event she said she never thought would happen there.

"All of sudden chaos just broke out," Bayne said. "There was a bunch of people running into the J.C. Penney mall entrance, and they were just screaming that someone was going around the mall stabbing people, and that there was blood everywhere."

Though the mall's security teams were on site, the security officers were not armed.

Initially, nine victims were counted. Chief Anderson Monday said the 10th victim was identified as investigators continued to search through additional security video.

The victim, a 21-year-old man from St. Cloud, was not badly injured, and he told police that because of the nature of his injuries, he didn't initially seek out medical attention and didn't notify police.

The other nine victims have been released from the hospital.

The stabbings took place in several locations within the mall.

Cop is 'clearly a hero'

Amid the chaos, Jason Falconer, an off-duty police officer from nearby Avon, killed the suspect as he threatened other shoppers.

Authorities said Adan, the attacker, had three previous encounters with police. According to Anderson, most of the encounters were for minor traffic violations, none of which led to an arrest. The police chief declined to provide further details about the attacker until more information was known.

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

"His heroic actions are exemplary of having witnessed what he did as the suspect was lunging at him with a knife," St. Cloud Mayor Dave Kleis said. "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."

JUST WATCHED Mayor: Off-duty officer who shot attacker a hero Replay More Videos ... MUST WATCH Mayor: Off-duty officer who shot attacker a hero 01:18

City changed forever

JUST WATCHED Sources: Device found at second location Replay More Videos ... MUST WATCH Sources: Device found at second location 02:15

Anderson said the attack will change the city forever.

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

After the attacker in Minnesota was killed, the police chief said two search warrants were executed at an address in St. Cloud, and the suspect's vehicle was impounded. Though the case may be closed soon, Anderson didn't see things going back to normal.

On the same day, explosions in NY, NJ

The mall stabbing was one of several incidents reported nationwide Saturday. In New York, an explosion ripped through the Chelsea neighborhood , leaving 29 injured. A second explosive device was found a few blocks away, authorities say.

In New Jersey, an explosion went off in a garbage can on the route of a Marine Corps charity run. Thousands of people were about to participate in the 5K race in Seaside Park. No injuries were reported.

The man suspected in the bombings in New York and New Jersey was captured Monday.

Ahmad Khan Rahami was charged with five counts of attempted murder of a law enforcement officer after a shootout Monday with police in Linden, New Jersey, Union County Prosecutor Grace H. Park said. He is also charged with second-degree unlawful possession of a weapon and second-degree possession of a weapon for an unlawful purpose.

Rahami is believed to be connected to pipe bombs found Sunday night in Elizabeth, New Jersey, sources said

'ISIS does not represent us'

After the Saturday stabbings, Lul Hersi stood outside the Crossroads Mall, waiting to find out if her son was among the victims.

Fear washed over the Somali-American mother, not just for her son's well-being, but also because of the potential backlash against her community.

"This has been a dark day; it is a day we will never forget," said Hersi. "ISIS does not represent us. It does not represent Islam, and it does not represent Somalis."

Hersi said she hoped the tragedy would bring St. Cloud residents together, rather than divide them further.

"Let us unite as one Minnesota," she said. "Please let's spread love instead of hate."