A Facebook post ahead of the Trenton Art All Night festival warned of impending violence — and it’s unclear if state or local officials were aware of the warning ahead of the early morning shootout.

As CrimeOnline previously reported, an ongoing “neighborhood beef” in Trenton is believed to have precipitated the gun violence, which injured 22 people including a 13-year-old child, who is reportedly in critical condition. An unnamed gunman was killed, likely by police.

Philly.com reports that witnesses observed an elevated police presence from about midnight until 2:45 a.m., when the gunfire began.

Earlier on Saturday, a Facebook post cautioned people to stay away from the annual event, which reportedly draws between 20,000 and 30,000 attendees to New Jersey’s capital city.

Councilman-at-large Jerell Blakely showed Philly.com a Facebook post warning of the expected violence.

“Please. Please. Please. Do Not Go to the Art All Night. They will be shooting it up,” the post read.

It is not known who posted the warning. Blakely told the news outlet that in addition to the post, he was aware of “online rumblings” about expected violence at the 24-hour art festival.

Mayor-elect Reed Gusciori addressed the violence outside of a church service Sunday morning.

“It’s a concern,” Gusciori told reporters. “We are about to enter the summer and we have to change the mindset of Trenton so that people don’t solve things with violence, particularly gun violence.”

In addition to the 13-year-old boy, three others injured with gunshot wounds are in critical condition, ABC 6 News reports.

The Mercer County’s Prosecutors Office Homicide Task Force is investigating the mass shooting event.

[Feature image: AP Photo/Mel Evans]