By Darran Simon, CNN

(CNN) -- As a trauma surgeon, Dr. Andre Campbell has patched up victims of gun violence for decades, privately venting with colleagues about the epidemic.

Those private conversations became public Tuesday.

Campbell, who helped treat victims injured in a shooting at the YouTube headquarters in California hours earlier, made pointed comments about gun violence in a press conference about victims of the shooting.

"To think that after we've seen Las Vegas, Parkland, the Pulse nightclub shooting, that we would see an end to this, but we have not," Campbell, an attending trauma surgeon at Zuckerberg San Francisco General Hospital and Trauma Center, told reporters.

Three people suffered gunshot wounds in the shooting on the campus in San Bruno, California, south of San Francisco, according to San Bruno Police Chief Ed Barberini. One person injured her ankle, Barberini said. The female shooter died from an apparent self-inflicted gunshot wound, the chief said.

Campbell said gun violence is a problem that needs to be addressed. He also chided the media for not paying attention to other instances of gun violence.

"Gun violence happens every day throughout the United States. It happens here in San Francisco. It happens in the Bay Area. It happens all over the country," Campbell said. "But I don't see you guys out here because I'd like to make sure that people know that we got a serious problem that we need to address."

"I don't have all the answers ... at least we're having a discussion about it nationally," he said. "This is a real problem."

Hospital spokesman Brent Andrew said a 32-year-old woman was in serious condition, a 27-year-old woman was in fair condition and a 36-year-old man was in critical condition.

Campbell said the patients injured in the shooting at the YouTube headquarters suffered multiple injuries and were not in surgery at the moment.

"This is a terrible day in the United States," said Campbell, a professor of surgery at the University of California, San Francisco, School of Medicine.

Campbell said once again, the hospital -- the only level 1 trauma center in San Francisco -- was confronted with a mass casualty.

The hospital dealt with multiple shooting victims in each of the past two weeks, Campbell said. The incidents included a fatal shooting at a San Francisco barbershop.

"I didn't see all these cameras out here ... last week when I was here," he said.

"That's the problem, when something like this happens, which is terribly unfortunate, then you guys come out," Campbell said. "The reality is we have to deal with this all the time. We have to deal with the families."

Emergency medical providers generally define a mass casualty as an incident in which the number of casualties exceeds the resources available to deal with them.

The patients were awake and aware of what happened, Campbell said.

When asked if they said anything when they arrived at the hospital, Campbell said: "No, other than shocked like we are ... every time these terrible things happen."

In an interview with CNN, Campbell said he wanted to speak about the issue of gun violence in all communities.

"We kind of quietly do our job and we don't say a whole lot," he said. "But today just seemed like it was a day where people wanted to hear what was going on."

He added: "We as trauma providers, we are just saddened by the fact that this is a persistent problem."

Campbell grew up in Queens, New York, at a time when the city struggled with gun violence.

His interest in the sciences led to him to study pre-med at Harvard University. He graduated in 1980.

Campbell earned a medical degree five years later from the University of California, San Francisco.

He returned to New York to work as a resident at Columbia Presbyterian Medical Center, where he often treated victims of gun violence.

"I felt that I'd be able to make a difference in people's lives becoming a trauma surgeon," he told CNN.

He hasn't treated victims of nation's mass shootings like colleagues in other hospitals, but he has seen his share of gunshot victims over the years.

At Zuckerberg San Francisco General Hospital, he recalled seeing 10 to 15 gunshot victims often on weekends about a decade ago, he said.

"It happens with such regularity. It's unbelievable," he said of gun violence.

"We need to work together to find a solution," Campbell said.

Soon after he spoke to reporters, colleagues and doctors worldwide sent him warm text messages and emails.

"I just echoed what they feel," he said.