A 15-year-old boy charged with knife offences after a fatal stabbing at the Sydney Royal Easter Show has been released on bail.

Last night a 17-year-old working at the show was stabbed to death near the adult carnival rides about 8pm.

Another teen, aged 16, caught up in the brawl was also stabbed and suffered a leg injury. He is in a stable condition.

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This afternoon the 15-year-old was released from Parramatta Children's Court on the condition he does not come within one kilometre of the showgrounds at Homebush.

NSW Police do not believe he was responsible for the stabbing and are still looking for those responsible.

"We believe there is someone we still need to identify who is responsible for the stabbing," Superintendent Danielle Emerton said earlier today.

"It may be one person, it may be multiple people."

She called for people who had been at the show last night who may have footage of the incident to come forward to police.

The Royal Agricultural Society of NSW (RAS) has announced additional security and safety measures, including heightening the police presence and "increasing the visibility of metal detectors" to avoid any further violence occurring at the show.

Other security measures that were decided on include more random hand-wanding and bag checks, closing the main carnival at 9.30pm, making the twilight ticket arrival time earlier as well as increasing lighting.

"The RAS has a zero-tolerance policy towards any anti-social behaviour onsite and we will continue to work closely with NSW Police throughout the Show to uphold patron safety," the statement added.

The RAS said the main carnival will reopen tomorrow.

The general manager of the Sydney Royal Easter Show, Murray Wilton, said he received a phone call about "one minute past eight" last night about the fight.

"I, and my CEO, made our way directly to that area. Police and ambulance had already arrived, they got to the scene probably within about two minutes," he told 2GB's Jim Wilson.

"It was an horrific experience for everybody."

Mr Wilton was asked how someone would be able to bring a knife, which appears to be quite large based on videos shared online, into the showgrounds.

"How do you get a knife into a complex like this? You would think that it would be difficult, but, things can be thrown over the fence, a knife doesn't necessarily have to be made out of metal, so it's not going to be detected by metal detectors," he said.

He added it would be "impossible to physically pat down or search every person" with about 77,000 people coming through the gates yesterday.

Mr Wilton also said organisers are "tired" of young people – not children but teenagers – using the show to sort out their personal differences.

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'Confronting' attack not thought to be random

Investigators at this stage believe the stabbing was not a random attack, and involved two groups of people who were known to each other and met in an intentional confrontation.

NSW Ambulance Inspector Mark Whittaker said when paramedics arrived the 17-year-old was in cardiac arrest, having suffered a traumatic chest wound.

"Paramedics performed CPR and a number of other critical interventions at the scene before loading the patient for transport to Westmead Hospital, unfortunately despite best efforts he couldn't be resuscitated," he said, in a statement.

"There's no doubt this would have been a very confronting scene for the dozens of witnesses who were out to enjoy an evening at the Royal Easter Show."

Carnival area still closed

The adult carnival area remains closed today, though the rest of the show will stay open.

The Royal Agricultural Society said anybody who had a Tuesday pass to the show could use it on any other day instead if they chose to.

Anybody with reserved seating who chooses to not attend will be offered a full refund if they contact ca********@************om.au.

In a statement, the RAS, which runs the Show, said it was "shocked and saddened" by the incident and extended its sympathies to the death teen's loved ones and friends.

The RAS said it would work with police to ensure show-goers would be safe, but that there was already a "massive" police presence at the event.

It is nonetheless set to be "ramped up" for tomorrow night, Sydney Royal Easter Show general manager Murray Wilton said.

Police appealed for anyone with footage or information to contact Crime Stoppers on 1800 333 000 or at the website.