US police have charged a 16-year-old student with shooting three others outside a US school apparently in retaliation for beating him in a drug-related robbery inside the building last month.
Anjohnito Willett Jr is in custody facing four counts each of attempted homicide, aggravated assault and reckless endangerment.
He is also charged with illegally possessing a gun as a juvenile.
Police Lieutenant Kevin Kraus said Willett wounded three students and shot at a fourth as they were heading to a car to drive home from classes at Brashear High School, Pittsburgh.
Mr Kraus said school police investigated the October 18 robbery but could not file charges because Willett refused to identify his attackers, telling police he wished to settle matters himself.
The wounds of the victims – aged 16 and 17 – appeared to be non-life-threatening, according to police.
Six people were taken in for questioning, Pittsburgh public safety director Michael Huss said about two hours after the shooting.
None of the victims immediately spoke or co-operated with police.
All were listed in good to stable condition at city hospitals, she added.
Brashear is a high school with about 1,400 students and 100 faculty.
The school was locked down briefly, and students were released to their parents about 90 minutes after the shooting.