Streets in south Brisbane remain in lockdown, as police negotiate with a man inside a Sunnybank home.

Heavily-armed specialist offices were stationed outside the Dyson Avenue property from 11am yesterday, as experts attempted to talk to the man and bring an hours-long stand-off to a peaceful resolution.

It is believed the man is armed and a woman and a toddler are also inside the house.

An exclusion zone remains in place with residents asked to follow the advice of police.

Sources have told 9News the situation began when police went to the property to talk to the man, and he met them at the door with a gun.

It is understood police are not sure if the weapon is real or a replica.

Acting Inspector Mick Ackery said yesterday the man inside the home had a weapon and police were working towards a peaceful resolution.

"We're prepared to deal with the situation for as long as it takes to ensure the safety of the community and anyone inside the house," he said.

The tactical crime squad, detectives and other specialist police are assisting police on the scene.

Residents in nearby streets were forced to shelter inside their homes for much of yesterday, as police issued an emergency declaration just after 11am.

The declaration under the Public Safety Preservation Act is bounded by Dyson Avenue, Geddes Place, Beenleigh Road and Ganda Place.

Members of the public were urged to avoid the area.

Trains on one of Brisbane's busiest routes, the Beenleigh line, were also delayed.