By Jay Croft, Shawn Nottingham and Joe Sutton

CNN

(CNN) -- They came for a night of music and dancing. They left by fleeing past wounded club-goers lying on a bloody floor.

Shortly after 1 a.m. Sunday at the packed Cameo Night Club in Cincinnati, a DJ called for security over and over, one man recalled later.

In all, one person was killed and 16 others were injured by gunfire, Cincinnati police chief Eliot Isaac said on Monday morning. Five people remain hospitalized; two are in "very critical" condition, and three are in serious condition, Isaac said.

Police identified the slain man as O'Bryan Spikes, 27.

Police said several people had been able to sneak guns into the club and they believe more than one person was involved in the shooting. They said the incident developed from a dispute that started earlier in the day and later escalated.

The shooting was not related to terrorism, authorities said. But Mayor John Cranley said that made little difference to club-goers.

"...If you were in that bar or restaurant and people start shooting in a crowded room, what difference does it make to you what the motivation of the shooter was?" Cranley said. "We live in a city and a country where you should be able to go out and have a good time and not be terrorized by gun violence."

Several victims were undergoing surgery, Cincinnati Police Sgt. Eric Franz told CNN Sunday morning.

Police do not have any suspects in custody but are interviewing witnesses.

"I'm very confident that we will find those that are responsible for this," Isaac said.

'A lot of chaos'

Cameo is in the former home of a gay bar called Adonis, which closed in 2012.

It is in the city's East End area, on the Ohio River Scenic Byway near Cincinnati Municipal Lunken Airport, where it sits amid used auto parts yards and marinas.

Cameo hires off-duty police officers for extra security. Two officers were stationed at the club's entrance and another two in the parking lot, Franz said.

Officers in those situations are allowed to provide security only outside the clubs, Police Chief Eliot Isaac said. Clubs are responsible for their internal security.

To get in, clubgoers had been searched with an electronic wand to detect hidden weapons.

A man who was inside told CNN affiliate WLWT that he heard the DJ calling for security, although the music hadn't stopped.

"It was just a lot of chaos, obviously, when the shots went off," Cincinnati Police Department Capt. Kimberly Williams said. "People (were) just trying to get out of harm's way."

To leave the club, some patrons had to flee past injured people on the floor.

Police found a "chaotic crime scene" as they looked for witnesses, many of whom took off when the shooting started, said Cincinnati Assistant Police Chief Paul Neudigate.

"Everyone that we can identify is being interviewed," he said.

Police are hoping witnesses will come forward to help identify suspects.

The packed parking lot and the crowds trying to drive away hindered fire rescue teams, Assistant Fire Chief Roy Winston said.

"You had a mass group of people leaving the scene," Winston said.

Some of the injured drove themselves to area hospitals, police said.

One patient was treated for a gunshot wound and released from Anderson Hospital, said Nanette Bentley, hospital spokeswoman. Another person walked into West Hospital with a non-gunshot injury and was treated and released, Bentley said.

'Just going to have a good time'

Cranley, the mayor, said his city is "deeply saddened by this tragedy" and urged community members to work together.

"People were just going to have a good time and ended up getting shot," he said. "That is totally unacceptable."

He added, "This is a tragedy that has struck other communities and now it has struck Cincinnati. Our hearts are broken but our spirit is not."

The Cameo nightclub allows admission to anyone over the age of 18 on Friday nights. Saturday nights are for those who are 21 and above and promoted as "grown and sexy" night.

Cameo has a history of violent incidents, WLWT reported.

"We are aware of it. It (the club) has had some challenges in the past," Neudigate said.

Multiple assaults were reported at Cameo from 2014 to 2016, affiliate WXIX reported.

Worst US mass shooting so far this year

The incident is the worst mass shooting, in terms of the total number of victims, so far in 2017, according to Gunviolencearchive.org. There have been 71 mass shootings in the US this year.

In Cincinnati, there have been at least nine mass shootings since 2013. The most recent was February 28, when six people were shot at an apartment building in the Northside neighborhood.

The Bureau of Alcohol, Tobacco and Firearms is helping Cincinnati police with this investigation.

"Saddened to learn about last night's shooting in Cincinnati," Ohio Gov. John Kasich tweeted. "Our prayers are with the victims and families of all of those involved. I've instructed our administration to offer any assistance the state can provide."

CNN's Azadeh Ansari and Eric Levenson contributed to this report.