A man who was fatally stabbed in the neck at the Church of Scientology headquarters in Sydney has been described as a "beloved member" of the Church.

Key points: A 16-year-old dropped a sharp 25cm kitchen knife after police drew their taser

A 16-year-old dropped a sharp 25cm kitchen knife after police drew their taser Police claimed the boy had been involved in a domestic incident on Wednesday

Police claimed the boy had been involved in a domestic incident on Wednesday That's why he was being escorted from the Church of Scientology premises

A 16-year-old boy was arrested after allegedly stabbing two men, killing one, at the organisation's headquarters in Chatswood, shortly after midday.

The two victims were Church employees, according to police, and were taken to Royal North Shore Hospital, where one died from a wound in his neck.

Detective Chief Inspector Simon Jones said the teen had been asked to leave the Scientology premises.

"On being escorted down the roadway a knife was produced and with that knife he stabbed a 24-year-old who we believe to be a Taiwanese male in the neck," Detective Chief Inspector Jones said.

"He also caused some lacerations to an older gentleman also escorting him from the premises."

The centre is the largest Scientology facility outside the United States. ( ABC News )

Police could be seen leading the 16-year-old out of the complex on Greville Street in handcuffs, with paper bags covering his hands.

Detective Chief Inspector Jones said the reason the boy was removed from the premises was "solely in relation" to a domestic altercation that occurred on Wednesday.

In a statement, the Church of Scientology said the "very unfortunate matter" was now in the hands of police.

"We cannot make any further comment beyond the fact that the victim was a beloved member of our Church," the statement said.

"The Church is providing the police with any assistance needed in their investigation."

Police drew taser

The 16-year-old is at Chatswood Police Station assisting with inquiries.

Detective Chief Inspector Jones would not confirm whether the boy was a member of the Church of Scientology but said he had a "lawful reason" to be there before being asked to leave.

He said officers had to draw their tasers but they were not discharged as the boy cooperated with orders to drop his knife on the driveway.

It is alleged the knife was about 25 centimetres long.

Sorry, this video has expired Police speak to media after stabbings at Scientology centre

NSW Ambulance Inspector Carolyn Parish said paramedics treated a man who was "bleeding heavily from a neck wound".

He was stabilised before being taken to Royal North Shore Hospital in a critical condition.

"This type of injury is significant," Inspector Parish said.

"No paramedic is immune to this type of case and under the circumstances they worked tremendously well and they did exactly what they're trained to do."

She said the second patient sustained a minor laceration to his hand.

He has been discharged from hospital after treatment and has spoken to police.

The Church of Scientology acquired the Chatswood site for around $37 million. ( Supplied: Scientology.org )

The Chatswood Scientology Centre, known as the Advanced Organization and Saint Hill ANZO, was opened in September 2016 and is the "spiritual headquarters" for the Asia-Pacific region.

Spread over almost 13,500 square metres, the facility is the Church's largest centre outside the United States.

Described by the organisation as an "architectural masterpiece", the centre includes training facilities which can accommodate more than 450 people.

The building also hosts a "purification centre" with a gym and sauna, two recording studios, and 60 "auditing" rooms where Scientology counselling is delivered.