Police have given a government building in Sydney’s Oxford Street the all clear, after an earlier threat triggered an evacuation and major lockdown.

The building on the corner of Oxford and Wentworth streets, Darlinghurst, was evacuated after a threat was received about 4.40pm AEDT.

Emergency services cordoned off the area and began a floor by floor search of the building, which houses several government buildings, including the Department of Education and the Workers Compensation Commission.

About 7.30pm police announced that no suspicious items had been found and gave the building the all clear.

Police swarmed the Oxford Street building. (9NEWS)

The evacuation was precautionary and there was no information to suggest the threat was terrorism-related, a NSW Police Force spokesman said.

Officers remain at the scene.

Officers near Oxford Street. (9NEWS)

Earlier media reports suggested a gunman had entered the building.

Marked police cars near the building. (9NEWS)

Traffic near Oxford Street. (9NEWS)