An unassuming life before Dahir Adan's rampage in a Minnesota mall

People who knew Dahir Adan said he seemed to live a relatively quiet life. Photo / Washington Post

Nothing seemed awry when Dahir Adan told his family that he was going out to buy an iPhone on Saturday night.

It's unclear what time he put on a security guard's uniform like the one he wore while working a previous job at a nearby appliance factory. And it's unclear what was going through the 20-year-old's head when he walked into a shopping mall in the small Minnesota city where he'd grown up, wielding a knife.

But inside, police said, Adan went on a chaotic stabbing rampage, injuring 10 people before an off-duty police officer shot him in a Macy's store.

In their first public statement on Monday night (US time), Adan's family said they were experiencing the same "deep shock as everyone else is in the state of Minnesota".

"We are devastated by the incomprehensible tragic event of last Saturday evening," the family said in a statement read aloud to reporters by the family's attorney, Abdulwahid Osman.

'He was going to buy an iPhone'

As police and FBI agents on Monday continued to investigate the Saturday-night attack at the Crossroads Center mall, they were also attempting to understand what could have driven a young Somali American man who had been in the United States since he was a toddler, to commit such an act of violence.

According to Haji Yussuf, a local community leader who spoke to the family, Adan left no obvious clues. "The family said he was happy, joyful, worked full time, did well in high school. The last time he went out, he said he was going to buy an iPhone," Yussuf said.

People who knew Adan said he seemed to live a relatively quiet life in this town 70 miles northwest of Minneapolis. He played soccer with friends at a St. Cloud high school, studied at a nearby state university and worked as a security guard at an appliance factory two miles from home.

Residents here were stunned by the attack, during which Adan referred to Allah - God - and asked one shopper if he was Muslim, police said. Authorities have not confirmed a link to any terrorist groups, but a news agency tied to the Islamic State asserted responsibility for the attack, calling Adan was "a soldier of the Islamic State".

The group said Adan was responding to the Islamic State's "calls to target citizens of countries belonging to the crusader coalition". The FBI said it was investigating the attack "as a potential act of terrorism," but officials in Minnesota said they had found no direct links.

"We haven't uncovered anything that would suggest [he was not a] lone attacker at this point," St Cloud's police chief, William Blair Anderson, said Sunday at a news conference.

Adan's family, who said they were committed to cooperating with law enforcement, also asked St Cloud's residents "not to rush to judgement or conclusions," their attorney said.

The 10 people injured in the attack - eight men and two women, between the ages of 15 and 53 - survived, including a 21-year-old St Cloud man whom police identified late Monday, and who was not counted in earlier reports.

Police officers did not definitively name Adan as the suspect, but his father, Ahmed Adan, and some in the city's Somali American community identified him as the attacker.

'This is what drives some of this anger sometimes'

Adan moved with his family from Kenya to the United States at age 2 and grew up in St Cloud, said Abdul Kulane, of the Central Minnesota Community Empowerment Organisation. He graduated from Apollo High School in 2014, where he was a skilled athlete in basketball and soccer, said Khader Omar, one of Adan's Apollo High classmates, who is also Somali.

Community leaders say the ethnically diverse high school has one of the largest Somali student populations in the area. But bullies sometimes pick on the Somali students.

"There are incidents of discrimination. This is what drives some of this anger sometimes," Yussuf said of the handful of Somali American men who have engaged in extremist violence. Some teens have reported being called "ISIS" or "terrorist," he said.

On Sunday night, roughly 24 hours after Adan's rampage, a truck flying a Confederate flag and several motorcycles drove laps through some of St Cloud's predominantly Somali neighborhoods, revving their engines in a manner that was meant to intimidate, said Jaylani Hussein, the Minnesota director of the Council on American-Islamic Relations, a Muslim advocacy group.

Adan, who was an informations systems major at St Cloud State University, was roughly halfway through his studies, a school spokesman said. But he had not enrolled for the fall.

A spokesperson for Securitas Security Services, which employed Adan to work as a part-time security guard at a local factory complex, said he quit the job in June.

Adan's Facebook profile, which was taken down Monday, had only two photos available to the public. One, in which Adan stood with a group of friends, appeared to be from his high school graduation.

Adan lived in a run-down brick apartment building, where nearly all of his neighbors were also Somali, across from a strip mall on the west side of St Cloud. According to Yussuf, he lived with his parents and multiple siblings.

'No one is talking right now'

The sounds of residents' conversations leaked through thin walls and into the building's hallways on Monday, but no one wanted to talk about Adan or what happened.

"No one is talking right now," one man said from his doorway .

"Do you have children?" asked another man, who was standing outside with a friend. "Then you don't know what this is like for them."

Some in Minnesota's Somali community have long expressed suspicion of law enforcement and charge that Somali youth are stigmatised as terrorists, and baited by FBI informants.

Earlier this year, a federal court in Minneapolis convicted three young Somali-American men of trying to travel to Syria to join the Islamic State. Six others indicted in the case took plea deals.

Adan's few previous encounters with police had been minor traffic violations, police said.

Rumors swirled in St Cloud's Somali neighborhoods on Monday, as residents speculated over missing details, and wondered why police had not released video footage.

Abdi Nor Adan, a 27-year-old Somali American college student who was not related to Adan, said he had heard that Adan had used a nail file to carry out his attack. Another man suggested Adan had been provoked into a mall fight.

Adan's attack began just after 8pm Saturday when he began slashing at shoppers with a knife "big enough to hurt someone," said Anderson, St Cloud's police chief.

Near the end, he lunged at Jason Falconer, an off-duty police officer, who shot Adan multiple times, Mayor Dave Kleis said. Police said Monday that Adan struggled to get up three times before he died.