McNeil High School educational assistant Tyler Johnson, 20, was arrested Wednesday for allegedly having sex with a 15-year-old freshman student on a playground, an affidavit released Thursday.

The affidavit states that on April 9, Johnson had sex with the student on the playground of Brushy Creek Elementary School in Round Rock.

The school was notified about the alleged relationship on Tuesday and the educational assistant was removed from the campus and the Round Rock Independent School District said a report was made to law enforcement.

The assistant, identified by a district spokesperson as Tyler Johnson, began working at McNeil in August 2015 and the district said he served as an educational assistant for a small number of students.

Round Rock ISD said Johnson had passed a Texas Department of Public Safety background check and employment reference checks prior to employment. The school district said Johnson is no longer employed by Round Rock ISD.

Williamson County Jail records state Johnson has been charged with sexual assault of a child. He is being held in lieu of $150,000 bond.