PHOENIX — A man questioned in a string of Phoenix freeway shootings is not the prime suspect and investigators are pressing ahead with leads in a case that has left the city on edge for two weeks, authorities said Saturday.

A 19-year-old man from a Phoenix suburb who was detained Friday at a convenience store near Interstate 10 is a person of interest, but Arizona Department of Public Safety spokesman Bart Graves declined to say what led police to question him. The man has been booked into jail on an unrelated marijuana possession charge.

Many Phoenix drivers have avoided freeways since the 11 confirmed shootings began Aug. 29, mostly along I-10, a major route through the city. Eight of the cars were hit with bullets and three with projectiles that could have been BBs or pellets. One girl’s ear was cut by glass as a bullet shattered her window.