By Todd Melby

ST. CLOUD (Reuters) - The family of a Minnesota man who wounded 10 people in a knife attack at a mall before being killed by an off-duty police officer said on Monday they were devastated by their son's actions.

Dahir Adan, who local media reported hailed from a Somali family that had settled in the United States, carried out the attack in the Crossroads Mall in St. Cloud, Minnesota on Saturday night, according to his family. Police said the assailant was 20 years old and lived in the area.

"We are devastated by (the) incomprehensible tragic event of last Saturday evening," said a statement from Adan's family distributed to reporters at a news conference by the family's attorney, Abdulwahid Osman.

"As we mourn the death of our son, Dahir Adan, who was very dear to us, we are in deep shock as everyone else is in the State of Minnesota. We express our deepest sympathy and condolences to all those injured," it read.

A news agency for the Islamic State on Sunday called Adan a "soldier of the Islamic State." U.S. President Barack Obama told reporters at a news conference the FBI was investigating the attack as a "potential act of terrorism."

The Minneapolis Star Tribune quoted Ahmed Said, executive director of the Somali American Relations Council, saying they did not know whether religion motivated Adan, “but we know he is a Somali.”

On Monday evening, authorities identified a 10th victim of the attack who they said did not notify police or seek out medical attention for his injuries. Hospital officials on Monday said all the other victims had been treated and released.

Jama Alimad, 65, a prominent figure in St. Cloud's sizeable Somali community, described Adan as a, "typical American kid, outgoing, nice."

"Something triggered it. We don't know what," Alimad said of the attack.

Somali community leaders in St. Cloud, about 60 miles (100 km) northwest of Minneapolis-St. Paul, condemned the attack and Adan's family expressed concern about possible backlash.

"Our family loves St. Cloud and this State and we are (an) integral part of the fabric of this society. Therefore, we urge citizens of St. Cloud and of this State to stay united and let the law enforcement agencies gather the facts and do their job," Adan's family said in a statement.

Jason Falconer, a part-time officer from the nearby Avon Police Department as well as a fire arms instructor and competitive shooter, was at the mall on Saturday and was the one to fatally shoot Adan. Obama on Monday praised Falconer's actions.

Authorities said Adan was wearing a security uniform when the attack took place. Securitas, a security company that does not provide security to the mall, said in a statement Adan was a former part-time employee who resigned in June.

A spokesman for St. Cloud State University said Adan had pursued a degree in information systems and was enrolled in the college in 2014, but withdrew in the spring of 2016.

The mall stabbing was one of three attacks over the weekend including a Saturday night bombing that injured 29 in Manhattan and a bomb that exploded in New Jersey earlier on Saturday.

Obama said there was no known connection between that attack and bombings in New York City and New Jersey over the weekend.

(Writing by Timothy Mclaughlin in Chicago; Additional reporting by Michelle Conlin in New York and by Ben Klayman in Detroit; Editing by Curtis Skinner and Simon Cameron-Moore)