As Isis issued a statement describing Abdul Razak Ali Artan as a “soldier”, investigators were probing the background of the 20-year-old, a Muslim who was a lawful permanent resident of the US and a student at Ohio State University.

The Associated Press said officials had so far found no strong evidence linking Artan to other known militant individuals, cells or groups. Police have said they are seeking a motive for the attack, carried out by means of a knife and a car.

Police believe the attacker may have been self-radicalised (AP)

Yet officials claim the young man’s actions were similar to a pattern of lone-wolf individuals who behind other such United States, such as the gunman who shot to death 49 people at a nightclub in Orlando, Florida, in June, and the man who killed four US Marines and a Navy sailor in a shooting in Chattanooga, Tennessee, last year.

A federal official said that while Isis had claimed responsibility in other attacks, investigators had seen no evidence so far that the militant group’s role was anything more than inspirational.

Investigators were looking into a message posted on Facebook by Artan that contained inflammatory statements about being “sick and tired” of seeing Muslims killed and reaching a “boiling point”, a law enforcement source said.

“Stop the killing of the Muslims in Burma,” Artan said in the Facebook post.

Violence in Burma has resulted in Rohingya Muslims fleeing across the border to Bangladesh amid allegations of abuses by security forces.

That post, as with all of those he publushed on Facebook, have been removed from the social media website.

Active shooter at Ohio university

Artan on Facebook also called Anwar al-Awlaki, a US-born radical cleric linked to al-Qaeda’s Yemen wing, “a hero”. Awlaki was killed by a US drone strike in 2011.

In its claim of responsibility for Monday’s attack at the university, located in the state capital, Columbius, the Isis' propaganda arm posted a photo of Artan wearing a blue shirt and sitting with greenery in the background. It described him as a soldier of the group.

“Brother Abdul Razak Ali Artan, God accept him, implementer of the Ohio attack, a student in his third year in university,” it read.

As Isis continues to lose swathes of territory in Iraq and Syria, its propaganda has been increasingly focusing on inciting attacks by supporters in the West. A video entitled "Slaughter the Disbelievers" was released over the weekend with instructions on how to carry out knife and bomb attacks, while an Isis English language propaganda magazine urged followers to use car rammings a fortnight before.

Ohio State University shooting Show all 16 1 /16 Ohio State University shooting Ohio State University shooting Crime scene investigators collect evidence from the pavement as police respond to an attack on campus at Ohio State University, Monday, Nov. 28, 2016, in Columbus, Ohio. (AP Photo/John Minchillo) AP Ohio State University shooting Ohio State students duck under police tape after a shelter-in-place notification was lifted following an attack Monday, Nov. 28, 2016, at Ohio State University in Columbus, Ohio. (Joshua A. Bickel/The Columbus Dispatch via AP) AP Ohio State University shooting Students leave buildings as police respond to an attack on campus at Ohio State University, Monday, Nov. 28, 2016, in Columbus, Ohio. (AP Photo/John Minchillo) AP Ohio State University shooting Students leave buildings as police respond to an attack on campus at Ohio State University, Monday, Nov. 28, 2016, in Columbus, Ohio. (AP Photo/John Minchillo) AP Ohio State University shooting Police respond to reports of an active shooter on campus at Ohio State University, Monday, Nov. 28, 2016, in Cincinnati. (AP Photo/John Minchillo) AP Ohio State University shooting Students leave buildings surrounding Watts Hall as police respond to reports of an active shooter on campus at Ohio State University, Monday, Nov. 28, 2016, in Cincinnati. (AP Photo/John Minchillo) AP Ohio State University shooting Law enforcement officials are seen outside of a parking garage on the campus of Ohio State University as they respond to an active attack in Columbus, Ohio, on November 28, 2016. Eight people were injured when an attacker apparently drove into a crowd at Ohio State University on Monday, triggering an hours-long lockdown before authorities declared the campus secure. Law enforcement shot and killed one suspect, according to local television station WBNS, which reported that police led two people out in handcuffs from a garage they had surrounded on the university's main campus in Columbus. / AFP / Paul Vernon (Photo credit should read PAUL VERNON/AFP/Getty Images) PAUL VERNON/AFP/Getty Ohio State University shooting A law enforcement official motions for people to leave the area outside of a parking garage on the campus of Ohio State University as they respond to an active attack in Columbus, Ohio, on November 28, 2016. Eight people were injured when an attacker apparently drove into a crowd at Ohio State University on Monday, triggering an hours-long lockdown before authorities declared the campus secure. Law enforcement shot and killed one suspect, according to local television station WBNS, which reported that police led two people out in handcuffs from a garage they had surrounded on the university's main campus in Columbus. PAUL VERNON/AFP/Getty Ohio State University shooting Law enforcement officials are seen outside of a parking garage on the campus of Ohio State University as they respond to an active attack in Columbus, Ohio, on November 28, 2016. Eight people were injured when an attacker apparently drove into a crowd at Ohio State University on Monday, triggering an hours-long lockdown before authorities declared the campus secure. Law enforcement shot and killed one suspect, according to local television station WBNS, which reported that police led two people out in handcuffs from a garage they had surrounded on the university's main campus in Columbus. PAUL VERNON/AFP/Getty Ohio State University shooting Law enforcement officials are seen outside of a parking garage on the campus of Ohio State University as they respond to an active attack in Columbus, Ohio, on November 28, 2016. Eight people were injured when an attacker apparently drove into a crowd at Ohio State University on Monday, triggering an hours-long lockdown before authorities declared the campus secure. Law enforcement shot and killed one suspect, according to local television station WBNS, which reported that police led two people out in handcuffs from a garage they had surrounded on the university's main campus in Columbus. PAUL VERNON/AFP/Getty Ohio State University shooting Members of the Columbus SWAT team work the scene around a parking garage on the campus of The Ohio State University Monday, Nov. 28, 2016, in Columbus, Ohio. ) AP Photo/Jay LaPrete Ohio State University shooting Students leave buildings as police respond to an attack on campus at Ohio State University, Monday, Nov. 28, 2016, in Columbus, Ohio. (AP Photo/John Minchillo) Ohio State University shooting SWAT teams and police respond to reports of an active shooter on campus at Ohio State University, Monday, Nov. 28, 2016, in Cincinnati. (AP Photo/John Minchillo) Ohio State University shooting Police respond to reports of an active shooter on campus at Ohio State University, Monday, Nov. 28, 2016, in Cincinnati. (AP Photo/John Minchillo) Ohio State University shooting Students leave buildings surrounding Watts Hall as police respond to reports of an active shooter on campus at Ohio State University, Monday, Nov. 28, 2016, in Cincinnati. (AP Photo/John Minchillo) Ohio State University shooting Law enforcement officials are seen outside of a parking garage on the campus of Ohio State University as they respond to an active attack in Columbus, Ohio, on November 28, 2016. Eight people were injured when an attacker apparently drove into a crowd at Ohio State University on Monday, triggering an hours-long lockdown before authorities declared the campus secure. Law enforcement shot and killed one suspect, according to local television station WBNS, which reported that police led two people out in handcuffs from a garage they had surrounded on the university's main campus in Columbus. PAUL VERNON/AFP/Getty

Artan, who was born in Somalia, arrived in the United States in 2014, said a federal official. Ohio State University Police Chief Craig Stone said Artan was 20 years old.

Investigators believe Artan may have lived for as long as seven years in Pakistan. Somali refugees often spend some time in Pakistan before coming to the United States, another official said.

Investigators were trying to assemble a full picture of Artan's associates and recent activities, according to federal officials.

Two people remained in hospitali at Ohio State University Wexner Medical Centre, a spokeswoman said on Tuesday. Two others were at the Riverside Methodist Hospital. None of the victims have life-threatening injuries, officials said. Seven people have been released.