A Boston-area youth minister was fired Friday from Boston English High School following his arrest this week for an alleged execution-style shooting of a 17-year-old student after an argument over a drug deal. The Rev. Shaun O. Harrison, 55, allegedly employed the student to sell drugs and has been charged with attempted murder. The student survived and is reportedly being treated at Boston Medical Center.

The father of eight pleaded not guilty to charges of assault with intent to murder, assault and battery and unlawful possession of a firearm in a Suffolk County courthouse, according to Boston.com. The shooting occurred Tuesday, when Harrison and the student left Harrison’s Pompei Street home in Roxbury, Massachusetts, and began walking toward Magazine Street. Harrison told the student they were going to meet up with women and pick up marijuana, but it was allegedly a trap.

“He had told the victim that they were going to a house to get marijuana and meet up with some girls,” Assistant District Attorney David Bradley said, according to the Boston Herald. “There was no one else on the street and he was shot in the back of the head. Then Mr. Harrison fled the scene.”

The bullet grazed the victim’s head and the incident was recorded by a nearby surveillance camera. Police said the student told them that Harrison was his mentor and that he had been selling drugs for Harrison for several months prior to the shooting.

At the time of the incident, Harrison was in charge of substance abuse and anger management programs at Boston English High School, a public school in the city, according to the New York Post. He previously held jobs in the city’s public school system as a community liaison and a teaching aide. Harrison was an active member of the local community and often volunteered at anti-violence rallies around the city.

One of Harrison’s neighbors said she regularly saw young people going in and out of his apartment after midnight and that she often smelled marijuana coming from his apartment. Police also arrested three men in their 20s at his apartment and found drugs and illegal firearms there. Harrison and two of the other suspects had distinct, matching Latin Kings gang tattoos on their necks, but Harrison's sister told reporters following his arraignment that he had no affiliation to any gang.

A Suffolk County judge set Harrison’s bail at $250,000, although the district attorney’s office wanted it set at $750,000. Authorities are seeking a search warrant for Harrison's apartment. He was also ordered to wear a GPS tracking device, stay under house arrest and away from the victim in the event he is released from custody. Harrison is due back in court April 6, according to Boston.com.