It happened at 6:15 a.m. Tuesday at UCSF Parnassus campus.
RELATED: 'Perfect child': Family of 6-year-old boy shot, killed watching SF fireworks asks for justice
Two surveillance images have been released showing the suspect but at this point his whereabouts are unknown.
"I saw all this yellow tape and the cops saying you can't come in here," says Gabrielle Lim who works at UCSF and had to use a different entrance to get inside.
Police say there was a fight between two men inside a medical building lobby at UCSF Parnassus. The victim then exited the building and collapsed on the sidewalk. A nurse performed CPR on the man but he was pronounced dead a short time later in the ER.
VIDEO: SF woman attacked in front of home by man believed to be homeless
"It's crazy times that we're living in for sure but outside of a hospital it's pretty surprising," says Thomas Forbes who was at the medical building visiting a patient when we talked to him.
Police haven't given a motive or said how the person died. Those who work at UCSF Parnassus say they are scared. Jennifer Dudley says she was recently assaulted by a man on her way to work.
"I was attacked by someone who appeared to be homeless or someone who was just released from the ER," says Dudley. She went on to say, "there is a lot of homeless people that hang out in the corridor, they sleep on the benches, I saw people doing drugs in there, exposing themselves in the morning, they come and there is no one regulating the situation."
RELATED: Tech billionaire funding network of 1,000 security cameras around SF addresses privacy concerns
It's unclear if the suspect is homeless but police are hopeful that someone recognizes him.
ABC7 did Crime Map the area within a half-mile of the UCSF Parnassus Campus and found there have been four assaults and one robbery within the past month.
Read full press release below: