With nearly 900 people in southern, eastern and northern Ethiopia already reported dead or missing from flooding in the past two weeks, officials warned the toll was likely to climb as poor weather hampered relief operations.
Unable to land in many areas because of the floods, elite troops hung by ropes and ladders from helicopters over the devastated Southern Nations, Nationalities and People's state searching for survivors and bodies.
"We have two helicopters flying at low altitude, and airborne troops are descending on ropes to look," said Tegaye Mununhe, chief police inspector for the state's Southern Omo region, adding that aid packages were being dropped.
He said the teams would either try to pluck those stranded from rooftops or trees in 14 inundated villages or radio their location to rescue crews in 15 small boats, manned by divers, swimmers and medical personnel.
"We are dropping food, fresh water and blankets to those who remain
stranded," Mr Tegaye told AFP from Jinka, about 780 kilometres southwest of Addis Ababa, adding the risk of water-borne disease was rising.
Banks burst on Sunday
At least 364 people were drowned and up to 20,000 stranded in the region when the Omo River and several tributaries swelled by heavy seasonal rains in the Ethiopian highlands burst their banks on Sunday.
Overwhelmed by the crisis, regional authorities desperately sought outside help as UN agencies and private aid organizations pledged to assist.
"We are trying to do everything we can, but the magnitude of the disaster is not something we can tackle by ourselves," said Governor Shiferaw Shegute.
The flooding in the south came after rivers burst their banks in the east, where 256 people were killed last week and some 250 are still missing, and in the north, where at least six people have died.
A total of 876 people have either been killed or are unaccounted for with tens of thousands left homeless, according to official tallies.