Two people are feared missing after a water bladder atop a dam wall burst in central Queensland.
Floodwaters are rushing downstream after the bladder of water holding 10,000 megalitres ruptured at the Bedford Weir, near Blackwater, about 200km west of Rockhampton.
The bladder sits on top of the weir to raise the level of water storage.
The water is expected to wash into the McKenzie River, a tributary of the Fitzroy River.
Queensland Police spokeswoman Nicki Devereaux said a search was underway.
"Police hold concerns for the whereabouts of two people," she told AAP.
Police, Queensland Fire and Rescue Authority crews, paramedics, and State Emergency Service volunteers, along with at least one local helicopter had rushed to the scene, Ms Devereaux said.
"We are using all possible resources, given the time of the day and the light available, to try and ascertain the significance of (any damage caused by the burst) and anyone that needs rescuing," she said.
Further details would emerge as rescue crews descend on the area and residents check for friends and neighbours in the wake of the dam burst, Ms Devereaux said.
"We're hoping, given the night-time and everybody getting together and doorknocking properties that we have a bit more solid information."
The effect of the rupture on the surrounding country and downstream of the dam is unclear, Ms Devereaux said.
"It would seem that the volume of water may be less than first thought and that any roads and road crossings may not be affected over the coming days of it travelling downstream, but I can't 100 per cent confirm that," she said.
Earlier, police had warned that a mass of water was travelling downstream towards the Fitzroy River Barrage, near Rockhampton.
"The water will travel quickly and in a large volume and may cause flash flooding at river crossings and bridges," police media said.
Police advise the public to stay away from the area until further notice, but they don't expect the flood to affect the Fitzroy River.
Central Highlands mayor, Peter Maguire, told AAP: "It's a disaster".
The mayor, who lives in Emerald, said he was not on the scene so could only go by reports made to him that up to four people are missing following the deluge.
The Bedford Weir holds 22,900 megalitres of water.
The bladder was on top of the concrete dam wall, Mr McGuire said.
Blackwater, a mining township with a population of 5,000, was earlier declared the state's 13th natural disaster area after being bruised and battered on Friday by a ferocious storm packing hailstones and the size of melons.
