One person drowned and three others went missing after a boat they were on, capsized in Kolab reservoir near Podagada jetty under Semiliguda Police limits of Koraput on Thursday.
Four others were safely rescued from the river.
The ill-fated country boat with eight passengers on board was en route to Tentulipadar from Mukhigudai when the mishap occurred.
The police and ODRAF team have launched a search operation to rescue the missing persons.