Nearly 300 students and staff at two major southern California universities are under quarantine as health officials warn they might have been exposed to measles. CBS News correspondent Carter Evans reports that at Cal State Los Angeles, 198 are quarantined. Seventy one students and 127 staff members might have been exposed in a campus library.

At the University of California, Los Angeles, 76 students and six faculty are still at risk after a contagious student attended classes.

Officials at UCLA said a student contagious with measles attended classes for three days earlier this month, potentially putting hundreds at risk.

"It's crazy to see that that's happening in a place that I spend time studying. It was supposed to be eradicated," said Nolan Origer, a UCLA student.

The university has identified dozens who may have been exposed. They're being quarantined until medical records can prove their immunity.

"You need to stay at a specified location, and you need to stay there until such time that you are deemed as not likely to come down with the disease," said Dr. Muntu Davis, a health officer at the L.A. County Department of Public Health.

That could be anywhere from 24 hours to seven days. Earlier this month, someone with measles entered a library at Cal State L.A. Health officials have contacted some 200 staff and students who worked there.

"They say they have 2,000 visitors in that library a day. Most of them don't sign in or out, so we have a lot of exposure to folks that we actually can't identify," said Dr. Barbara Ferrer, L.A. County Department of Public Health director.

While hundreds showed up for an anti-vaccine protest in the California capitol on Wednesday, the highly-populous state has managed to keep the number of measles cases relatively under control due to high vaccination rates, with 38 cases so far this year. Nationwide, the government has counted nearly 700 measles cases, roughly three-quarters of them in New York state, which had among the largest and longest-lasting outbreaks since the disease was all but eliminated in 2000.

"I have been hyper-aware of all the symptoms and stuff. Like, I've been itchy and I'm like, 'do I have measles?' I've been super worried," said Sarah Kiamanesh, a UCLA student.

Both UCLA and Cal State LA have said the buildings affected no longer pose a threat to students. More than three-quarters of California's known measles patients were either not vaccinated or did not receive the recommended two doses of vaccine.