The local CBS affiliate said 22 people were wounded, and that four of them were in critical condition, including a 13-year-old boy. The Trentonian said that the venue for the festival was strewn with broken glass and other debris.
The organizers shared a message on Facebook Sunday. The prosecutor said multiple weapons were recovered inside the venue, including a handgun that had an extended capacity magazine, "meaning that it contained more ammunition than is permitted under New Jersey law".
Officials are also investigating reports of an attempted carjacking that occurred nearby.
The Mercer County's Prosecutors Office Homicide Task Force is taking over the investigation as there was an officer-involved shooting, officials said.
Gennie Darisme was getting ready to leave the festival when she heard gunfire and saw people running.
City Councilman Jerell Blakeley said there were "whisperings" on social media Saturday that "there would be some issue" at the annual art event.
When she was walking back to her auto after the shots stopped, Darisme said she saw someone bleeding on the ground, in handcuffs. Attendees reported a heavy police presence at the site after midnight and up to the time of the 2:45 a.m. shooting. "I've been going for the past several years, never anything like this", Lennon said.
Onofri said 17 of those were gunshot wounds. It was in its 12th year and included over 1,500 works of art, graffiti, and live murals.
Knapp, the event volunteer, said she had scrapes on her knees and elbows and a small bump on her head, but she's grateful she wasn't shot.
USA 'will not be a migrant camp': Donald Trump
She wrote: "I appreciate the need to enforce and protect our worldwide boundaries, but this zero-tolerance policy is cruel". He cited immigration for causing political instability in Germany and said that crime in Germany was "way up".
"I go, 'It sounds like fireworks.' He said, 'No, that's gunfire'".
A police officer stands in front as other officers inspect the crime scene at the Roebling Market.
The festival, which was scheduled to continue through Sunday, has been canceled.
The statement also said they were "shocked" and "deeply saddened".
Capital Health Systems, which operates Capital Health Regional Medical Center in Trenton, said "numerous" victims were being treated. "They bandaged him up and whisked him away", Nicolo added. They were in various stages of being released, she said.
The injured were taken to area hospitals, where some had been treated and released.
"My sympathy goes out to the victims and their families", said Trenton Mayor Eric Jackson during a press conference.
Governor Phil Murphy visited the scene Sunday afternoon, tweeting "Because of faith, because of community, we will rise above this senseless violence".