It happened on Center Terrace in the South Ward late Friday night.
Investigators said the man was armed with an automatic weapon when he got into a scuffle with a Newark police sergeant.
The sergeant was on a field inspection of patrol units when the suspect approached him.
Authorities said the suspect was carrying a Tec-9 semi-automatic. The sergeant tried to disarm him, which led to a scuffle between the two men.
During the fight, authorities said the suspect repeated tried to draw his weapon.
That is when the sergeant pulled out his gun and shot the suspect once in the side.
The suspect remained in critical condition at University Hospital on Saturday morning.
No names have been released.