Seventeen of those injured suffered gunshot wounds, Mercer County Prosecutor Angelo Onofri said Sunday morning. A 13-year-old boy and three other people are in critical condition.
The Mercer County's Prosecutors Office Homicide Task Force is taking over the investigation as there was an officer-involved shooting in the incident, officials said.
It happened around 2:45 a.m. Sunday at the 'Art All Night Trenton 2018' festival at the Roebling Wire Works Building on the 600 block of South Clinton Avenue.
VIDEO: Aftermath of Trenton arts festival shooting
Onofri says multiple individuals who were attending the event opened fire in the venue. Several weapons have been recovered.
Authorities have identified at least two suspects in the shooting. One, a 33-year-old man, has been pronounced dead; the other was taken into police custody. They say there could be more suspects and are questioning witnesses.
Trenton resident Angelo Nicolo spoke to Action News about what he witnessed.
"And all of a sudden, my brother goes to me, 'You hear that gunfire?' I go, 'It sounds like fireworks.' He said, 'No, that's gunfire.' Next thing you know, we turn around and everybody's running down the street. All hell broke loose," Nicolo said.
Nicolo said he saw one person with a gunshot wound to the leg.
"I saw two police officers escort a guy that got shot in the leg; they bandaged him up and whisked him away before the ambulance came here. It was pretty gnarly," Nicolo said.
Trenton fire crews as well as medics, including some from Bucks County, were called to the scene.
The 'Art All Night Trenton 2018' event started 3 p.m. Saturday and was scheduled to run until 3 p.m. Sunday. The festival showcased 1,500 pieces of local art, live murals, live art instructions and 60 plus musical acts performing on three stages.
Officials say approximately 1,000 people were in the area at the time of the shooting and there were no metal detectors at the building.