An Arizona teacher allegedly used a school messaging app to start a sexual relationship with a 13-year-old student, police say.

Las Brisas Academy elementary teacher Brittany Zamora instructed her sixth-grade students to message her on an app called Class Craft because she was going to be bored at school one day, reported AZ Central.

However, for one student in particular, the conversation with Zamora, who was 27 at the time, went from casual to flirtatious to extremely explicit.

Records obtained by The Arizona Republic reveal Zamora and the boy had sex multiple times in her car and classroom, including one time when another student was present. During her class, the two engaged in sexual touching while other students were watching a video, records show.

Zamora was arrested in March 2018 on suspicion of sexual misconduct after a monitoring app on the boy's cellphone alerted his parents to illicit texts between the two.

Zamora, now 28, surrendered her state teaching certificate in December. She continues to be held in a Maricopa County jail on a $250,000 bond, according to public court records.

In her messages with the boy, the two would often talk about what sexual acts they wanted to do to each other.

"She said she wanted to give me a blow job and my stuff is really big and stuff like that," the boy told an interviewer.

He also said that after Zamora kissed him after class once, the relationship quickly evolved into a sexual one.

The boy told officials Zamora "touched his stuff" at her desk while she pretended to look for something in a drawer. Other students were just feet away while this happened.

One night, the teen snuck out of the house after midnight to meet Zamora in her dark red Mazda, where they performed oral sex on each other. However, when Zamora’s husband called and said he was on his way home, the two stopped.

The next night they met again and briefly had sex before her husband called and she left.

One day, the 13-year-old and his friend stayed after school to rehearse for a talent show when Zamora kept them in the classroom. The teacher and boy began kissing while his friend stood and watched. Eventually, she asked the friend to stay and make sure no one saw as they had sex in the classroom.

A lawsuit filed by the parents last month alleges three students told Las Brisas Principal Timothy Dickey they believed Zamora was in a relationship with the student.

The boy eventually admitted to his parents that he and the teacher had sex.