The sand laden dumper rammed against the three-wheeler head-on near Bhalupali junction in which the two sisters and another person died on the spot, they said.
Their brother, the driver of the autorickshaw and two other occupants were battling for their life in VSS Medical College Hospital at Burla, the sources said.
While the two sisters belonged to Sambalpur town, the other deceased hailed from Jharsuguda.
The driver of the dumper had been arrested and the vehicle seized, the sources said adding tension prevailed in the area following the road mishap.
