WAHPETON (AP) - Agencies in Minnesota and North Dakota are investigating a fish kill in a tributary of the Red River.

The kill was discovered late Monday afternoon on the Bois de Sioux River, a couple of miles south of Wahpeton.

Area fisheries supervisor Arlin Schalekamp of the Minnesota Department of Natural Resources says the kill involves only carp.

Schalekamp says the kill could have been caused by low oxygen levels in the river or a disease. But he says investigators won't know until samples are analyzed in St. Paul, and that could take a couple of days.

Both the Minnesota DNR and the North Dakota Game and Fish Department are investigating.