The measles outbreak in rural West Texas has grown to 124 cases across nine counties, the state health department said Tuesday. There are also nine cases in eastern New Mexico.

A child who was not vaccinated has died from measles in West Texas, the first death in an outbreak that began late last month and the first from measles in the U.S. since 2015. The death was a “school-aged child who was not vaccinated” and had been hospitalized last week,

At least 124 cases have been identified in Texas since late January, mostly among children and teenagers who are unvaccinated or whose vaccination status was unknown.