NEW JERSEY, United States (AP) — An all-night arts and music festival turned deadly Sunday morning when gunfire erupted in a crowd, sending people stampeding and leaving one suspect dead and 20 people injured, authorities said.

Sixteen people were treated for gunshot wounds, said Mercer County Prosecutor Angelo Onofri this morning. Four of those, including a 13-year-old boy, were in critical condition.

Two suspects opened fire around 2:45 am during the Art All Night Trenton festival that showcases local art, music, food and films. One of the suspects, a 33-year-old man, was killed, authorities said. Another suspect is in custody.

Today, there was crime scene tape surrounding the site of the old warehouse building that now shares a parking lot with a supermarket, bank and laundry facility.

Ernie Rivas has owned a shop near the site of the shooting for 17 years and said he came back from the beach this morning when he heard what happened.

“I’ve never seen this happen. It’s bad, I feel bad, especially on Father’s Day,” Rivas said.

Theresa Brown said she’s been volunteering at Art All Night for 12 years and has never seen or heard of violence like this. She said she was leaving her volunteer shift around 2:00 am and heard “pop, pop, pop.”

“I thought it was a car backfiring,” she said.

She returned to the scene around 7:00 am and saw the police.

Art All Night Trenton began Saturday afternoon and was scheduled to conclude this afternoon. The remainder of the festival has been cancelled.

“We’re very shocked. We’re deeply saddened. Our hearts ache and our eyes are blurry but our dedication and resolve to building a better Trenton through community, creativity and inspiration will never fade. Not tonight. Not ever,” festival organizers posted on social media today.

A spokeswoman for St Francis Medical Center in Trenton said 10 victims were being treated there for minor injuries. She said they were both men and women, ranging in age from 17 to 48. They were in various stages of being released, she said.

One man with a gunshot wound was transferred to Cooper University Hospital in Camden.

Capital Health Systems spokeswoman Kate Stier said they have “at least 16” patients there, including the 13-year-old boy in critical condition. That total may not include people treated and released.