The measles outbreak centered in northwest Texas grew to 683 cases and spread to three new counties on Friday, according to health officials. The latest update from the Texas Department of State Health Services adds 20 new cases since the agency's last update on Tuesday.

The Texas health department reported 683 cases of measles in the state on Friday, an increase of 20 since April 29, as cases of the childhood disease surpass the 900-mark in one of the worst outbreaks in the country.

Since the measles outbreak began in West Texas, 87 people in Texas have been hospitalized, and two school-aged children have died.