Two other customers were also wounded, but survived the Thursday night attack that killed 45-year-old officer William Johnson.
Acting Police Director Samuel DeMaio said investigators believe the shooters intended to attack someone in the restaurant Thursday, but they're not sure who.
By midday Friday, authorities were still hunting for the suspects. Police canvassed the South Ward putting up posters for Crimestoppers, hoping a $20,000 reward would induce witnesses to come forward with details of the shooting.
The car from which the shots came sped off immediately, authorities said.
Police and city leaders were mourning.
"He is from our city. He lived in Newark. He is one of our own, up from the bricks. And one of our own, who dedicated his life to protect us, is slain in our streets," said Mayor Cory Booker. "We must work together to say this will never happen again."
Johnson, a police officer since 1995, was assigned to the department's video surveillance unit.
In this case, investigators are looking at surveillance video from inside and outside the restaurant to help solve the slaying of one of their own.
He was off-duty when he stopped by Texas Fried Chicken and Pizza to order something to eat.
The bullets came from a vehicle outside the restaurant about 9:50 p.m.
Besides Johnson, two other people were hit. A 21-year-old man was wounded in the stomach and was in stable condition at University Hospital.
A 19-year-old at the restaurant with her toddler was struck in the shoulder. She was released from the hospital by Friday morning. Her child was not wounded.
The slain officer grew up in Newark and continued to live in the city that often ranks as one of the nation's dangerous places. He had two daughters.
He was declared dead just after 3 a.m.
"The tragedy of this senseless killing is compounded by the fact that the victim, Officer Johnson, was a man who devoted his professional life to protecting the City of Newark and its residents from this type of violence," said state Attorney General Paula Dow.
