SHOREVIEW, Minn. (AP) - Officials with the Minnesota Department of Natural Resources are trying to determine what killed thousands of fish in Lake Owasso.

DNR spokesman Harland Hiemstra says there's no evidence of a chemical spill or toxins, and tests show that oxygen levels are normal.

Lake Owasso lies within Shoreview and Roseville in the northern St. Paul suburbs. Hiemstra says the lake is managed primarily for muskies.

Lake resident Les Hassler tells the St. Paul Pioneer Press he's counted thousands of dead fish since Lake Owasso froze last Tuesday.

The DNR says about 90 percent of the dead fish it's counted are small panfish, with a few bass and walleyes. Residents have pulled out a few dead muskies, too.

The spokesman says fish kills aren't unusual, and the DNR isn't too alarmed.