A Somali-born student who carried out a car-and-knife attack at Ohio State University might have been inspired by the Islamic State group and a former al-Qaida leader, investigators said Wednesday.

Law enforcement officials said that it’s too soon to say the rampage that hurt 11 people on Monday was terrorism. They said they aren’t aware of any direct contact between the Islamic State group and the attacker, Ohio State student Abdul Razak Ali Artan.

“We only believe he may have been inspired” by the group, said Angela Byers, the top FBI agent overseeing federal investigations in the southern half of Ohio.

Artan also might have been influenced by Anwar al-Awlaki, a U.S.-born cleric who took a leadership role in al-Qaida before being killed in a 2011 U.S. drone strike in Yemen, Byers said.

Al-Awlaki has been cited as inspiration by numerous terror suspects over the years, including the brothers who bombed the Boston Marathon, the Army psychiatrist who killed 13 people at Fort Hood, Texas, and, more recently, the man charged in bombings in New York and New Jersey.

Rep. Adam Schiff of California, the top Democrat on the House Intelligence Committee, said investigators are still going through Artan’s electronic devices, but it seems clears he was radicalized online.

He also said there doesn’t seem to be much time between the onset of Artan’s apparent radicalization and the attack, a period known in law enforcement and intelligence circles as “flash to bang.” That trend has disquieted law enforcement officials, who fear disaffected individuals are being inspired to violence after being only briefly exposed to radical ideology.

“This may be one of those cases which was just unpreventable,” he said, adding that there was no evidence yet to suggest Artan had been publicly communicating radical intentions over a long period of time.

He said the fact that Artan may have been inspired by a cleric killed five years ago shows the “limits of taking people off the battlefield.”

“As long as you have disaffected or alienated young people who are searching for something to belong to, the lure of this radical propaganda will continue to be very dangerous,” Schiff said.

The FBI said it was looking to verify whether Artan posted rantings on Facebook hours before the Ohio State attack criticizing U.S. interference in Muslim lands and warning of more Muslims in sleeper cells.

He did buy a knife the morning of the attack, but police don’t know if that was the weapon he used, investigators said.

The 18-year-old was fatally shot by a police officer shortly after driving into pedestrians and then slashing others with a knife. A preliminary autopsy released Wednesday showed Artan died from gunshots to the head and chest.

The officer was nearby because he had responded to reports of a gas leak in a building. Those reports appear legitimate and unrelated to the attack, said Mike Woods, a deputy chief with Columbus police.

The personnel file of the 28-year-old officer, Alan Horujko, contains high marks for the officer’s performance since he was hired in January 2015.

On Tuesday, a self-described Islamic State group news agency called Artan “a soldier of the Islamic State” who “carried out the operation in response to calls to target citizens of international coalition countries.” The Islamic State group has described other attackers around the world as its “soldiers” without specifically claiming to have organized the acts of violence.

“They have been known to take credit for incidents like this when the assailant is deceased and can’t refute that,” Byers said.

The investigation has not found that anyone else was involved in the attack or the planning of it, Byers said.

Authorities are trying to piece together a gap of several hours between the time Artan bought the knife at a Wal-Mart near his home and the attack.

What’s also unknown is why Artan targeted the campus and an engineering building, Woods said.

Artan was in his first semester on campus and enrolled in the business school. He was a refugee who spent several years in Pakistan before coming to the U.S. in 2014.

President-elect Donald Trump tweeted Wednesday that Artan “should not have been in our country.” Trump’s tweet did not elaborate.

Ohio State students continued to offer messages of support for the victims by writing messages on a board in the student union. Well-wishers using markers contributed Bible verses, famous quotations and sympathetic messages to the victims and police.

Three of the 11 people injured in the attack remain hospitalized and are expected to recover, according to the Ohio State medical center.

A leader of a Somali community association in Columbus said Tuesday that Artan had driven his siblings to school as normal Monday before the attack.

Artan’s mother said she didn’t know anything was wrong until police showed up at her door, said Hassan Omar, president of the Somali Community Association, relating an in-person conversation he had with the mother Monday afternoon.

Nothing seemed different about her son, who she said was enjoying his education, Omar said.

“He woke up and he went to school,” Omar said.

(AP)