The bridge over Vansadhara river at Gumuda, 60 km from Rayagada, collapsed disrupting traffic.
"The districts of Rayagada, Koraput and Malkangiri have been cut off from Berhampur following the collapse," said Additional District Magistrate of Rayagada, Ranjan Sharma.
Two elderly women were reported missing after they were washed away in the Madhumunda nullah near Chandrapur in Rayagada.
Besides Vansadhara, the Rushikulya and Nagavali rivers were in spate inundating large areas while the Tel, Hathi and Udanti in neighbouring Kalahandi had also wreaked havoc, officials said adding heavy precipitation in the catchment areas had triggered the deluge.
Meanwhile, the death toll in rain-related incidents in the state has risen to 17.
Several villages in Muniguda, Gudari, Gunupur and Padmapur blocks had been inundated by the swollen Vansadhara with eight villages marooned by the flood waters.
Relief has been provided to about 300 marooned villagers.
The flood waters had also entered a portion of Gunupur and Gudari towns.
The Vansadhara river, which was flowing above its danger mark at Gunupur was, however, receding.
A report from Berhampur said Rushikulya river had disrupted road communication at two places while three reservoirs in Ganjam district spilled over this morning.
The flood waters had overtopped the Bhubaneswar- Bhanjanagar road at Nuagam and NH 217 at Khadabhaga disrupting road communication between Aska and Berhampur.
While Rushikulya was flowing at 35.33 m against the red mark of 34.75 m at Aska this morning, the level was 17.45 metres against the danger mark of 16.83 m at Purushottampur.
Rushikulya had inundated four villages under Seragada block and three villages under Belaguntha block.
The reservoirs which were overflowing in Ganjam district were Daha, Dhanei and Baghua.
Heavy rains had been caused by the deep depression over the Bay of Bengal which crossed the Orissa coast near Paradip yesterday morning, Met officials said.