MERCED, Calif. (AP) — A male student stabbed and injured five people as classes got underway at a rural university campus in central California before police shot and killed him, authorities said Wednesday.

All those attacked at the University of California, Merced, were conscious when paramedics reached them, Assistant Vice Chancellor Patti Waid said. Two victims were taken by helicopter to hospitals, but their conditions were not immediately known, officials said.

The other three had injuries that were minor enough that they could be treated on campus, Waid said. Campus officials say some, but not all, of the victims are students.

They said the assailant was a student but had not confirmed his identity or provided a motive for the attack. Officials said they were still working out a timeline of events leading up to the stabbings, and it wasn't clear how the attack played out.

University senior Phil Coba, a student government representative, said numerous students told him that the stabbings started inside a classroom and continued outside before campus police shot and killed the attacker.

Authorities have not confirmed those accounts and have said the attack occurred outside a building as students went in to class shortly after 8 a.m. PST.

Student Alex Lopez was heading to class when he realized something was wrong on campus.

"I was listening to a podcast, and there was a break in talking, and I just hear a gunshot," he said.

He said police and first responders flooded the scene.

"You see this stuff all over the news and stuff and you see it happen to all these other schools," but you don't expect it to happen at your school, said Lopez, 21.

The school with more than 6,600 students is about 120 miles south of Sacramento in the farm-rich San Joaquin Valley. The campus in the city of Merced opened a decade ago and is the newest college in the University of California system.

It was erected in the state's farm belt in response to the burgeoning enrollment in the nine other University of California campuses. Regents also felt the mainly agricultural region was unrepresented by higher education. It was the first UC campus built since 1965.

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Elias reported from San Francisco.