A San Antonio ISD teacher was arrested on Monday for having an improper relationship with an 18-year-old female student, officials say.

Juan Carlos Ramos was charged with improper relationship between an educator and student, SAISD said.

Ramos taught at Edison High School. He has resigned from the district, where he worked since August of 2008.

In a statement released Monday, SAISD said, "This is a very serious allegation, and we want parents to know that the safety and well-being of our students is paramount."