"We have confirmation of two people killed for now," police spokeswoman Jenny Houser told AFP, adding that the identity of the victims was unclear.
"We have two victims," police spokesman Tony Im told AFP, adding that officers were searching the sprawling campus for an armed gunman.
Im said the shooting was reported shortly before 10 am in Boelter Hall, which is part of the school of engineering.
Dozens of police cars and tactical response teams rushed to the campus and ordered all students and staff to shelter in place.