Merced County Sheriff SWAT members on the University of California Merced campus after the attack. (Andrew Kuhn/Merced Sun-Star via AP)

The University of California at Merced student who went on a stabbing spree before he was fatally shot by police appeared to have “self-radicalized” and been inspired by the Islamic State, but he did not seem to have ties to any terrorist groups or been directed by anyone, the FBI said Thursday.

In November, 18-year-old Faisal Mohammad attacked one student in a classroom before attacking three others, authorities said. A campus police officer shot and killed Mohammad.

Federal investigators scoured Mohammad’s digital history and found that he appeared to have taken inspiration from terrorist sites and propaganda, the FBI said in a statement.

On Mohammad’s laptop, authorities said they found proof that he had visited websites related to the Islamic State, a militant group also known as ISIS and ISIL, and other extremist sites. They also found pro-Islamic State materials on his computer.

Investigators looking into the Merced attack said they have found no indication he was working with or guided by anyone else in the attack, which they believe he started preparing for at least a week before the Nov. 4 stabbing spree. They also said it was possible they could never answer the question of why he did this.

“After an extensive investigation of all available evidence, no ties to co-conspirators or foreign terrorist organizations have been found,” the FBI said. “Every indication is that Mohammad acted on his own; however, it may never be possible to definitively determine why he chose to attack people on the UC Merced campus.”

The stabbing spree occurred about a month before an attack in San Bernardino, Calif., about five hours south of the Merced campus. Authorities said the two shooters in that case, who gunned down 14 people in what was declared a terrorist attack, also appeared to be self-radicalized and not directed by any outside group.

When the stabbings at Merced occurred, Mohammad had a backpack with what the FBI called “a two-page, hand-written plan detailing his intentions to include taking hostages and killing students and police officers.” The bag also contained zip ties, a knife and a photocopy of an Islamic State flag.

After the attack, authorities said they struggled to find a motive for what happened. The four wounded victims — two students, a school adviser and a construction worker — suffered non-life-threatening injuries, officials said. Campus Police Chief Albert Vasquez called the episode “a sad and tragic day in UC Merced’s short history.”

Niraj Chokshi contributed to this report.

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