UPDATE | Motive still lacking for attack at OSU

COLUMBUS (AP) — The Somali-born student who carried out the car-and-knife attack at Ohio State University stewed over the treatment of Muslims while apparently staying under the radar of federal law enforcement, underscoring the difficulty authorities face in identifying and stopping lone wolves bent on violence.

Abdul Razak Ali Artan was not known to FBI counterterrorism authorities before Monday's rampage, which ended with Artan shot to death by police and 11 people injured, a law enforcement official told The Associated Press.

That's in contrast to several other recent attacks, including those in New York City; Orlando, Fla.; and Garland, Texas, in which those blamed for the bloodshed had previously come to the attention of federal agents.

Law enforcement officials have not identified a motive for the Ohio State violence but have suggested terrorism as a possibility. FBI agents continued to search Artan's apartment for clues.