University Hospital officials contacted Newark Police when a male victim entered the hospital around 11:50 p.m. Friday.
Police say before the hospital's alert, a ShotSpotter activated and detected about 20 rounds of gunfire in the area of Avon and Jelliff avenues.
Officers arrived and found a mixture of about 9 rifle rounds and 8 handgun shell casings just at the border of Newark's South and Central wards.
The victim suffered non-fatal gunshot wounds after the suspects fired at him using an AK-47.
Police said there were no other injuries reported and the suspects fled the scene.