"Measles is a highly contagious infectious disease that can be fatal in small children," Inslee said in his proclamation on Friday, adding that these cases create "an extreme public health risk that may quickly spread to other counties."

There were 34 cases of the measles in Clark County, which sits on the state's southern border, just across the Columbia River from Portland, Oregon. Officials said 30 of the cases involved people who have not had a measles immunization; the other four are not verified. Of the 34 cases, 24 are children between age 1 and 10. There are also nine suspected cases in Clark County.