So here’s the face of the Muslim killer who stabbed four people yesterday at UC Merced and was subsequently shot and killed by campus police:

According to Fox News, ISIS tweeted out praise for the Muslim killer:

As authorities worked to establish a motive for the 18-year-old college freshman who stabbed four people on a California campus Wednesday, more disturbing details emerged about the attacker.

Faisal Mohammad, who was killed by University of California Merced police, was described by at least one witness as smiling as he slashed at victims, called a loner by a fellow dorm resident and drew praise Thursday from a Twitter account associated with ISIS, which just last week released a series of videos calling for lone wolf stabbing attacks.

“May Allah accept him,” read a tweet in Arabic from a Twitter account that terrorism experts say has carried previous ISIS propaganda, just minutes after Mohammad’s name was divulged by campus authorities.

Investigators were expected to reveal more information in a news conference later Thursday morning.

“He had a smile on his face, he was having fun,” a construction worker who helped stop the attacker told CBS 47.

A suitemate said Mohammad “didn’t talk much.” Speaking to KFSN, Andrew Velasquez said he never saw the stabber walking to class with anyone, adding, “Every time I would try and say something he would just ignore it.”

Campus police shot and killed Mohammad, a computer science & engineering major who graduated from Wilcox High School in Santa Clara last June. Police detonated his backpack and are testing a substance inside, KGO reports.

The four victims are expected to survive. Authorities say Mohammad was armed with a hunting knife, and that its blade was 8 to 10 inches long.