Police confirmed they responded to second and third-hand reports of an incident in Cowlishaw Street in Tuggeranong from about 9.50am.

An employee from a Tuggeranong business told DHS security they had seen a person with a gun.

Police, who closed streets in the town centre for a period, said officers had entered the building and spoken with security. They were unable to substantiate the reports, and left by 10.45am.

Police subsequently lifted the road closure in Cowlishaw Street and said there was no longer any incident in the area.

An ACT Policing spokeswoman said the incident was not a hoax and police had responded appropriately to a report of a firearm.

"Further inquiries revealed it was a misunderstanding and information was reported to police third hand."

The spokeswoman said the investigation into the incident had ended and no-one was taken into custody.

Police were confident there was no weapon or firearm in the area.

The DHS later issued a statement confirming the lockdown had been lifted.

"The Department of Human Services has reopened buildings in the Tuggeranong area after
taking security precautions while a potential security issue was investigated this [Wednesday] morning," it said.

"Immediate action was taken to alert ACT police and close buildings after an unconfirmed report of suspicious behaviour in the vicinity of a DHS building on Cowlishaw Street at about 9am.

ACT Police investigated and advised there was no security threat. All buildings returned to normal operation at about 10.40am."

The Department of Social Services confirmed it also locked down its two Tuggeranong premises after the unconfirmed report.

The DSS buildings were released from lockdown about 11am.

Despite road closures in the town centre, a Tuggeranong Hyperdome spokeswoman said the shopping centre remained open during the ordeal.

"It was business as usual for us, thankfully," she said.