The flooding, which affected the village of Kasaba, comes at a vulnerable moment for the Central African nation. Rwanda-backed M23 rebels have intensified an offensive in the eastern region since the start of the year, with thousands killed in fighting in the first two months of the year.
Samy Kalodji, administrator of Fizi territory in South Kivu province where the village is located, said late on Saturday that reports from the area "indicated more than 100 deaths."
The affected area is still under the administration of Kinshasa and is not among the zones taken by M23.
Didier Luganywa, spokesperson for the South Kivu government, said in a statement the flooding incident occurred between Thursday night and Friday when torrential rains and strong winds caused the Kasaba river to overflow its banks.
The statement gave a toll of 62 confirmed deaths with 30 injured.
Local officials said the Kasaba area was only accessible via Lake Tanganyika and was not covered by the mobile phone network, which could delay humanitarian relief efforts.
