At least two people have been killed at the University of California’s Los Angeles campus in what police called a murder-suicide.
The shooting took place at the university’s engineering school on Wednesday morning. It prompted a campus-wide lockdown and forced hundreds of terrified students to hide in buildings.
Both victims were male and found with gunshot wounds, said Los Angeles police chief Charlie Beck.
"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.
A female told the Reuters news agency that she took shelter inside the student health center about 10 minutes after she had arrived for work there.
"Everyone is really on edge and contacting loved ones to let them know we are safe," said Erica Roberts, a sophomore economics major from Rockville, Maryland.
"I’m trying to stay in contact with all my friends on campus to make sure they are OK. Everyone is just terrified."
Police were investigating the deadly incident and it was not clear whether the victims were students or staff members.
The United States has been gripped by a surge in the number of deadly shootings over the past couple of years.
The government’s efforts to impose stricter gun control laws have proven futile.
The US Centers for Disease Control and Prevention (CDC) has put the total number of domestic gun deaths at 1.5 million between 1968 and 2014.
According to the CDC, firearms are the cause of death for more than 33,000 people in the United States every year, a number that includes accidental discharge, murder and suicides.