Five bodies wrapped in two plastic bags were pulled from the lake on Sunday and Monday. Two other bodies were recovered on August 19.
Officials have not yet confirmed the identities.
"The victims are not Burundian citizens because the bodies are coming from Akagera River flowing from Rwanda," Jean Berchmans Mpabansi, a Burundian official, told BBC. But no one from Rwanda has been reported missing, Rwandan police say.
Local fisherman assert there are more bodies, with residents claiming to have seen upward of 40 in the water.