A student who stabbed four people at a California university was inspired by the so-called Islamic State group, the FBI has said.

Authorities said Faisal Mohammad, 18, was probably "self-radicalized," and was not in direct contact with the militant group.

Police shot and killed Mohammad after he carried out the November attack at the University of California, Merced.

The FBI said agents found IS propaganda on Mohammad's computer.

Mohammad was also found with writings that showed that he had planned the attack at least a week in advance. All of his victims survived the attack.

A month later, a husband and wife killed 14 people at a staff training event in San Bernardino.

The FBI has also described Syed Rizwan Farook and Tashfeen Malik as being "self-radicalized" yet inspired by IS.