DC Police are investigating allegations of sexual abuse in the District’s summer youth employment program.

Two female participants in the program claim they were sexually assaulted on their job sites.

The Washington Post reports that one incident occurred on Wednesday at the headquarters of the Department of Employment Services (DOES), and the other occurred on Friday, at a public high school.

Assistant police chief Peter Newsham said the victim working at DOES was a 17-year-old, employed at the headquarters as part of the program. Officials said Thomas Nelson, 54, of Northeast Washington, a file clerk, was arrested and charged with second-degree touching of a minor by a person in a position of authority.

In the Friday incident, a 19-year-old woman alleged that she was touched inappropriately by a construction contractor at Anacostia Senior High School in Southeast Washington. No arrest has been made and the incident remains under investigation.

Mayor Vince Gray expressed outrage over the allegations.

“These alleged acts are extremely alarming, disappointing and reprehensible,” Gray said in a statement. “We take very seriously any allegations of improper conduct and criminal acts against our youth. We will not tolerate, for a moment, the victimization of our young people in the Summer Youth Employment Program who have the right to expect this to be a wholesome, healthy and enriching work experience.”

According to NBC Washington, program staff will reemphasize safety measures, and supervisors were reminded to keep careful watch over participants.