A measles outbreak in West Texas has topped 120 cases and resulted in the first U.S. death from the illness in a decade.

At least 124 cases of measles have been identified in Texas since late January, mostly among children and teenagers who are either unvaccinated or whose vaccination status is unknown, officials say.

A child who was hospitalized with measles has died from the illness in West Texas, state and local health officials announced Wednesday. It is the first death in a measles outbreak that has infected more than 120 people since late last month.