Home destroyed in southern Qld bushfire

Several hundred people have been told to prepare to leave as a bushfire threatens their homes, farms and businesses in southern Queensland.

Queensland Fire and Emergency Services issued a watch and act warning to about 300 people living in Millmerran Woods, Cypress Gardens and Millmerran Downs, southwest of Toowoomba.

"Conditions could get worse quickly," firefighters said in the warning on Tuesday.

"Firefighters are working to extinguish the fire, however you should not expect a firefighter at your door."

The fire has burnt through about 400 hectares, destroying homes and several sheds after flaring up on Monday night. It is slowly burning in dry bushland near Millmerran Woods.

"Once the smoke had cleared and we could actually go in and assess some of the properties, we confirmed two dwellings that have been destroyed and a caravan and a number of smaller outhouses and buildings and some of those properties as well," Queensland Fire and Rescue Service manager Wayne Waltisbuhl told the ABC.

He said the fire escalated quickly late in the afternoon as firefighters struggled with challenging conditions.

"A number of our crews really suffered from heat stress ... really testing conditions for firefighters out here at the moment - we have temperatures in the high 30s, really low humidity is and that is really testing them."

Firefighters say some properties remain under threat and water-bombing aircraft could be deployed against the blaze, which is likely to impact the community later on Tuesday.

Authorities warn smoke could reduce visibility and lead to poor driving conditions as roads are closed off in the area.

An evacuation centre has opened at the Millmerran showgrounds for people who need to flee their homes.

Deputy Premier Steven Miles said fortunately, no one had been hurt in the fire as he thanked emergency services for their work protecting lives and homes overnight.

"It just reminds us again how well served our state is by our first responders, working through the night to keep those properties safe," he said.