Two men died on Wednesday in a murder- suicide at the University of California's Los Angeles campus, prompting a lockdown and a massive security deployment at the sprawling facility.
Los Angeles police chief Charlie Beck said both victims were found with gunshot wounds in an office on campus. At least three shots were fired and a gun was found at the scene.
"At about 10:00 this morning a homicide and a suicide occurred in the engineering facility... Of the UCLA campus on the south side," Beck told reporters. "It appears it is entirely contained."
"There is evidence there could be a suicide note but we don't know at this point," Beck added.
The shooting prompted a campus-wide lockdown as hundreds of officers and tactical response teams as well as federal agents rushed to the university, where students are in the middle of final exams.
All university classes were cancelled for the day and the lockdown was lifted at around noon.
"We are in the process of releasing the campus back to the students," Herren said. "They are in their finals. This is a very stressful time for them, and we're trying to alleviate that."
Some 43,000 students are enrolled at the massive UCLA campus, according to its website.
Students and staff on campus were urged to take cover when the shooting was first reported as officers went from building to building searching for a possible active shooter and other victims.
Many students and staff could be seen walking out of buildings with their arms raised.
Students said they received alerts on their phones from the university notifying them of the shooting and advising them to take shelter.
Several visibly shaken students told local media of hiding in bathrooms or classrooms as the situation unfolded.
Authorities also placed the city of Los Angeles on a tactical alert which means that police throughout the area could be mobilised. A nearby elementary school was also placed on lockdown.
Officials said they were still piecing together what prompted the murder-suicide.
"Tragically so many of these active shooter situations end like this," Beck said.
The White House said President Barack Obama had been notified of the California shooting and had asked his team to keep him updated on the situation.
Gun violence is a part of daily life in the US where readily-available firearms claim about 30,000 lives each year.