Administrators say a 23-year-old teacher in San Antonio has died after collapsing at school before classes began for the day.
An autopsy has been ordered.
Officials said Villegas, who taught math, was with colleagues Monday morning in a work room when she collapsed.
A spokeswoman for the East Central Independent School District says Villegas was transported to a hospital, where she was declared dead.
Stevie Gonzales said district officials had no information on whether Villegas had any medical issues.