A suspected killer remains on the run and a 15-year-old has been charged after a brawl in which another teenager died and one was seriously injured after they were stabbed in front of crowds at Sydney’s Royal Easter Show.

Footage circulating on social media appears to show police performing CPR on the dying 17-year-old in the aftermath of the fight.

The teenager, who was working at the show, suffered a critical stab wound to his chest. He was given first aid at the scene by police before paramedics arrived.

The 17-year-old died while being transported to Westmead Hospital after Monday night’s horrifying fight.

A 16-year-old boy remained in hospital on Tuesday with stab wounds to his leg.

Another teen, aged 15, was charged on Tuesday while more – including the alleged killer – remain at large. Police believe further suspects were involved in what they described as a senseless and tragic targeted attack, involving two groups of teens.

The fight, which broke out in the crowded carnival ride area of the showground about 8pm on Monday, was believed to be gang related.

About 77,000 people attended the show on Monday.

Police Superintendent Danielle Emerton said the 15-year-old had been charged with carrying a knife in a public place, carrying a knife with intent and affray.

“We believe that there is someone who we still need to identify that is responsible for the stabbing,” she said on Tuesday.

“It may be one person, it may be a number of people.”

Police also believe more weapons might be involved but have seized only one knife so far. They have appealed for witnesses to help.

“There were thousands of people there, if you have information, please come forward,” Superintendent Emerton said.

“It’s a tragic incident. It’s going to have affected a family. This is a senseless act. This is a family event at the Royal Easter Show.”

A strike force has been established to investigate, with members of the Homicide Squad and Auburn detectives involved.

Chief Executive of the Royal Agricultural Society of NSW Murray Wilton apologised to patrons who witnessed the stabbing, saying it was a “horrific experience”.

“Someone’s lost their life at our house, and it’s disgraceful,” Mr Wilton said.

Closing the adult area of the carnival rides section on Tuesday was the right decision, he said. Security at the show would also be ramped up, with more police on site.

Metal detectors were used at the show but searching everyone and the bags of the 800,000 people who attended the show over 12 days wasn’t possible, he said.

NSW Ambulance Acting Chief Superintendent Stewart Clarke said the incident was confronting for paramedics, and crowds of revellers who were visibly distressed.

Other videos circulating on social media captured parts of the incident, including footage of boys brawling in a busy area by a lit-up a Ferris wheel, as groups of teenagers ran through crowds and a woman yelled, “Oh s–t”.

A photo circulating on social media shows the boy, apparently unrestrained, on the Free Fall ride. Photo: Supplied

Meanwhile, SafeWork NSW is investigating if the Free Fall ride should be closed for the remainder of the show after a four-year-old child was unrestrained while the ride was in operation.

A photograph showed the boy on the ride unharnessed when it was in mid-air, while three other children on the ride were restrained.

Fair Trading Minister Eleni Petinos said she had a zero-tolerance approach towards any operator who failed to provide the highest possible safety standards.

“The ride has been closed pending investigation,” she said.

-AAP