State police say three of the victims in the crash were dead by the time authorities arrived. The sole survivor remains in critical condition after he was flown to a Philadelphia hospital.
Outlaw said a gun recovered at the scene is believed to belong to the 22-year-old victim.
No arrests have been made and no information was released about the shooting suspects. Authorities are reviewing surveillance footage from the store and the area to gather additional evidence.
At the scene, police had taped off the area in front of the store and blocked off Fairmount Avenue between Sixth and Seventh streets. As cars drove north on Seventh Street past Federal Donuts, a man stood in the roadway with a sign that said, Stop shooting people.
Federal Donuts did not immediately comment on the situation at its North Philadelphia store. The business, owned by restaurant group CookNSolo, has six standalone locations in Philadelphia and four others at the Wells Fargo Center, Citizens Bank Park and two Whole Foods stores.
Research forthcoming in the Journal of Applied Psychology looks at how experiencing rudeness amplifies anchoring bias including in doctors decision-making.