More than 700 students and staff members at two California universities were under quarantine on Friday — an increase of about 400 from the day before — as officials continued steps to curb the potential spread of measles after an outbreak was declared in Los Angeles County.

The two universities — the University of California, Los Angeles, and California State University, Los Angeles — have been working with county health officials to identify and contact students and employees who may have been exposed to measles this month.

Those at risk of having contracted measles were given health officer orders — legal orders issued by county officials — to stay home and avoid contact with others as much as possible.