A male student has stabbed and wounded four people on a university campus in California before being shot dead, campus police said.
Police at the University of California Merced, which is south of the state capital Sacramento, said two victims were transported to a local hospital while the others were treated on campus.
It said that all victims remained conscious, but provided no details on their condition.
After first speaking of five injuries, the school later had a downward revision of the toll, on Twitter: "Correction 4 stabbed: 2 students, 1 staff member, 1 vendor. All expected to recover."
The Merced Sun-Star newspaper identified the assailant as a male student in his 20s.
Construction workers remodelling a campus building heard a scuffle in a classroom, and when one - identified as Byron Price, aged 31 - went to investigate, the assailant lunged at him and stabbed him, the Sun-Star reported, quoting the worker's father, John Price.
Price said his son, who was among those hospitalised, was expected to recover.
There was no immediate information on the possible motives of the assailant.
It was not clear whether the other victims were students. Initially, the university said all were students but later backed off from that assertion.
The university, which opened in 2005 and has about 6500 students, remained in lockdown, with classes cancelled for the day. Officers were searching the campus for possible other assailants.
Attacks on US college campuses have been far from rare, though firearms are more commonly used. A shooting on October 1 at a community college in Oregon left eight students, a professor and the assailant dead.