The ISIS militant group on Tuesday claimed responsibility for the attack a day earlier at the Columbus campus. Al-Awlaki was killed by a U.S. drone strike in 2011.
The attacker, Abdul Razak Ali Artan, used a car on Monday to plough into pedestrians at the school and exited the vehicle and stabbed other victims. He was an Ohio State student and a lawful permanent resident of the United States.
"At this time we are not aware of anyone else being involved in the planning of this attack, but the investigation continues," FBI Special Agent in Charge Angela Byers told reporters.
The Federal Bureau of Investigation was not aware of Artan as a potential threat to public safety before he carried out the rampage, she said.