NEW HAVEN, Conn. — A school bus driver here was arrested for reportedly leaving two special-needs students on a school bus on Thursday, police said.

The driver, Marilena Monroy, told officers that she was unaware there were still students on the bus, NBC Connecticut reports. Police told the news source that the students who were left on the bus were a 17-year-old girl who is nonverbal and has several health disorders, and a 16-year-old boy who has autism, according to the news source.

The boy called his mother and told her that he was locked inside the bus after the driver left them there. She tracked the location of the bus through his phone, drove to the bus, and called police. The police report said that the bus wasn’t running and that the windows were closed, NBC Connecticut reports, and police said that the outside temperature at the time was 90 degrees.

The students were alert and able to walk off the bus, but the girl was later taken to the hospital for further evaluation. Police told the news source that they viewed bus camera video, which indicated that the students were left inside the bus for at least half an hour.

Monroy was charged with two counts of risk of injury to children, according to NBC Connecticut.

Dr. Carol Birks, the superintendent for New Haven Public Schools, described the incident in a statement posted on the district’s website as an “unacceptable breach of established protocols” and stated that the Connecticut Department of Children and Families and First Student, in addition to school officials and the police department, responded to the scene.

Birks added in the statement that she visited the impacted families to confirm their well-being and express her concern for the students involved in the incident, and that the district is “working with all agencies to establish facts and support all layers of this investigation.”