A male teacher at Waltrip High School is under investigation for alleged inappropriate behavior.
Houston Independent School District has hired a third party law firm to investigate the allegations.
While the case is moving forward, a district spokesperson tells Local 2, the teacher in question resigned on Monday.
Students who heard about his resignation are stunned.
"He's the nicest person I've ever met at school. He's a great teacher," said Marek Markoski.
"He's a good teacher. He's a very good teacher," said one student.
Local 2 has learned who the teacher is, but we are not naming him because as of right now, he has not been charged with a crime.
"Once the investigation is complete, HISD will provide the investigative findings to the appropriate authorities," Houston ISD said in a written statement.
While the district isn't releasing details of the allegations. a source tells Local 2 the teacher is accused of having an improper relationship with at least one female student.
"I'm shocked. It doesn't sound like him at all," said one student.
According to HISD officials, the reason a third-party law firm is investigating is to determine if there was any criminal activity involved. If they do find evidence of criminal activity, then it will be forwarded to the appropriate authorities.
A call-out will be made to parents Tuesday evening, followed by a letter on Wednesday.