Sydney's city center is in lockdown after a man fell from Centrepoint Tower.

Witnesses working in nearby office buildings told Daily Mail Australia they were told to 'get away from the windows and to the center of the building', wrote dailymail.co.uk.

The man, who was on the Sky Walk, reportedly took off his harness and fell off the building to his death.

A spokesman for NSW Police told Daily Mail Australia there was a police operation underway after the death of a person in the Sydney CBD.

'Officers were called to a building on Castlereagh Street about 2.40pm on Thursday. 

Sydney Tower Eye have confirmed 'following an incident, the attraction is closed until further notice'.

Tourists arriving to complete the SkyWalk were turned away just before 5pm, with staff telling them there had been an 'incident'. 

An employee was heard saying 'we can't say what happened, if you can reschedule'. 

There are reports of a heavy police presence around Centrepoint Tower.

Witnesses have said there are two police helicopters hovering, one over Hyde Park and one further east but in line with Market Street. 

The heavy presence is also understood to include about six police cars and a rescue vehicle.   

NSW Ambulance are on the scene providing treatment to witnesses who are reportedly in shock.  

A report will be prepared for the coroner. 

Pitt Street Mall remains open.