Islamic State (ISIS) flag
Islamic State (ISIS) flagReuters

The Islamic State (ISIS) has claimed responsibility for Saturday's stabbing rampage in Minnesota, but investigators have uncovered nothing to tie the Somali American attacker to organized extremist groups, the local police chief said Tuesday, according to AFP.

The attack on Saturday by Dahir Ahmed Adan is being investigated as a potential act of terrorism, and a news agency with ties to ISIS said the rampage was carried out by one of its "soldiers."

But St. Cloud police chief William Blair Anderson told reporters that no connections to extremist groups have been found.

"We haven't uncovered anything that would suggest anything other than it was a lone attacker at this point," Anderson said, according to AFP.

He cautioned that the investigation was still ongoing, and that officials were combing through the 20-year-old Adan's life for clues.

An FBI spokesman echoed the same caution.

"As part of our investigation, we are looking carefully at possible motivations as to why Mr. Adan engaged in that attack," spokesman Kyle Loven told AFP.

The agency also said the FBI's Joint Terrorism Task Force was taking over the investigation from local law enforcement, in what it called a "customary" move.

Police say Adan stabbed 10 people with a knife at a shopping mall, until an off-duty police officer confronted him and shot him to death.

Members of the Somali refugee community in St. Cloud expressed shock that Adan would commit such violence, saying he had been a high-achieving student with no history of violence.

The attack in Minnesota came the same day as bombings in New York and New Jersey. Police wounded and captured a suspect, Ahmad Rahami, in connection with those attacks.

So far it does not appear that there is a connection between the Minnesota stabbing and the New York and New Jersey bombings.

Anderson stressed again that the attacks in Minnesota and the East Coast did not appear to be connected.

"Right now, we have not uncovered anything that would suggest there's a nexus between those events," Anderson said, according to AFP.