School had just started for the year on Monday.
A suspect approached the victim, 17, during dismissal. The encounter became heated, and the suspect produced a firearm, Baltimore Police Commissioner Michael Harrison said at a news conference on Friday.
The suspect, also 17, shot at the victim multiple times, Harrison said.
The alleged shooter ran down the street, and school police apprehended him after a short pursuit without “incident or injury,” Harrison said.
Authorities also recovered a firearm that the suspect was seen discarding, he said.
School police performed CPR on the student at the scene, who had life-threatening gunshot wounds, Baltimore Police said in a written statement. The victim was pronounced dead shortly after arriving at a local hospital, the statement said.
“This is an extremely tragic situation, beyond tragic, happening on the grounds of a school in the beginning of the school year,” Harrison said.
The person in custody is a student at another high school in the city, according to Harrison. Police have not yet named the victim or the suspect.
Baltimore City Public Schools CEO Sonja Santelises thanked police officers for apprehending the suspect “within seconds of the incident.”
The school’s safety plan was in place and school police were “at post” during dismissal, Santelises said. Police also said law enforcement were in the school yard during the shooting.
Harrison said the investigation is still ongoing and asked the public to contact the police with any information.