A Scientology headquarters in Sydney has gone into "damage control" a day after a teenage boy allegedly slashed the throat of a church member who had tried to escort him out.

The Church's $52-million Australasian headquarters in Chatswood was surrounded by extra security guards today after a boy allegedly stabbed two people about 12.30pm yesterday.

A 24-year-old man from Taiwan died after being found with a serious wound to his neck.

A 16-year-old has been arrested after the incident at Chatswood at 12.30pm. (AAP)

One man has died, and the other is in a stable condition after the alleged stabbing. (9News)

Another staff member, who also sustained injuries to his hands, was released from hospital today.

The men were allegedly stabbed while trying to escort the young man from the premises. The incident is believed to be related to a family dispute.

But for an organisation shrouded in secrecy it's attracted unwanted scrutiny.

Former Scientologist Paul Schofield said the church would be in "total damage control" as Taiwanese members attract a significant amount of money to the religion.

"It will be all about how they can spin this so that Scientology comes out, maybe not smelling like roses, but with the least amount of stink attached to it," Mr Schofield told 9News.

Police could be seen taking evidence bags to their cars this afternoon. (AAP)

Police officers from North Shore Police Area Command attended - one man suffered a wound to his neck, the other was injured on his hand. (9News)

The accused knifeman will undergo a mental health assessment.

Police said a 20-25 centimetre knife was used in the incident before officers cornered the boy. He had allegedly argued with his family members inside the church before the driveway attack.

“Police had to draw their taser but were not required to discharge the taser – he dropped the knife,” Detective Inspector Simon Jones said.

The boy was led to a police car barefoot with paper bags over his hands.

One man died in hospital, the other is in a stable condition. (AAP)

On its official website, the church said the "Ideal Advanced Organisation in Sydney provides advanced religious services to Scientologists from across Australia, New Zealand and the Asia Pacific region".

The massive 13,500 square metre building - which was opened in September 2016 - is the largest Scientology centre outside the United States.

The site formerly housed the National Acoustic Laboratory and was purchased by the church for a reported $37 million in 2014.