Provincial information officer Ferdinand Perez identified the lone fatality as Faustino Pungcol, a resident of Barangay Maasin.
Perez said the members of two families earlier believed buried alive in the mud and boulders were able to escape before the disaster occurred.
The municipal rescue and relief team identified the survivors as Alexander Halvasco, his wife Catalina and their children Marcos, 12; Rondy, 14; Jennilyn, 10; and Meralyn, 8, and Rosita Cadesal and her son, Dodo.
Agusan del Sur Gov. Eddie Bong Plaza earlier sent engineering, relief and monitoring teams to the remote area.
Agusan del Sur and Surigao del Sur suffered much from floods and landslides caused by days of continuous rains since the start of the new year.
Four Agusan del Sur towns and another one in Surigao del Sur have been placed under a state of calamity due to the heavy floods.
Engineer Romeo Momo, regional director of the Department of Public Works and Highways, said some P140 million is needed to rehabilitate roads and bridges damaged by the floods and landslides.