A man is in custody following an incident at Crown Casino this evening.
Police have stressed that there is an ongoing investigation.
"At about 3.30pm, police were called to an incident at Crown Casino," Acting Commander David Clayton said.
"They were called there in relation to a male with a backpack acting erratically.
"Police responded and the area was evacuated. A short time later, a 55-year-old male was taken into custody.
"There have been no injuries to the suspect, police or public as a result of this incident.
"Police currently have specialist service on site who are conducting safety checks of the area, prior to the area being declared safe.
"It is an ongoing police investigation and the incident has not concluded.
"We are asking the public to stay away from the South Bank end of Crown Casino if they can."
Police were unable to elaborate on what caused the behaviour to be classified as "erratic".
Multiple reports were made to police that the man was behaving "erratically", with the specialist response team on hand to assist.
Police have said that the man may have made some statements at the time of the incident, and are confirming what transgressed.
Nothing has been found in the backpack, but police have stated that it is yet to be cleared.
The nationality of the man has not been confirmed, according to AC Clayton.