The male suspect, 18, who was not identified, was being questioned by homicide detectives and had not been charged, said Officer Nicole Monroe, the spokeswoman.
Police did not release disclose a possible motive in the shooting.
The shooting occurred after 9 a.m. in the 1900 block of N. Patterson Park Ave., where several dilapidated houses have been demolished.
Neighbors and passers-by gathered behind yellow crime-scene tape as about 25 police cadets searched vacant lots and alleys for the weapon police believe was used in the shooting.
Malachi Williams Jr., who was doing construction work in a car wash nearby, said he had seen six or seven children being led by police officers out of the rowhouse and into vehicles.