At least seven people have died and dozens more stranded after an "inland tsunami" swept through the Darling Downs city of Toowoomba and the Lockyer Valley.

Others are stranded on rooftops waiting for rescues that could not start before first light today.

Police have confirmed that seven people have died in the flash floods that swept through the Toowoomba area in the state’s southeast yesterday afternoon.

Full details are not immediately available, but it’s known the dead include a woman and a boy, whose bodies were found dead in the Toowoomba CBD.

And in the nearby community of Murphys Creek, a man and a boy were found dead after being washed away from a house.