Indian Encampment Painting by U.U. Lindquist - Another Mystery to Solve

I picked up this painting just over a year ago, and in all this time I have not been able to find anything about either it or the artist. It is signed "U U Lindquist," or perhaps "U U J Lindquist," though I'm not sure. This painting is not titled. I call it "Indian Encampment." I'd guess it was painted sometime in the 1970's-80's. It's a bit more abstract than what I am usually drawn to, but the price and timing were right so it came home with me.

Depicted here are a group of three Plains Indian warriors sitting on horses that are standing in the river. In the distance are snow capped mountains and evergreen trees, and on the bank of the river behind them is a small group of tipis and three riderless horses grazing. At first blush the scene appears rather idyllic, though why the guys parked their horses in the river is a bit unclear. If you look closer however you can see that one of the fellows is holding a rifle in his hand, ready to aim and shoot. Something is going on here, but I don't quite know what.

If anyone knows anything about either this painting or the artist who painted it, please let me know! So far my research has been in vain.

Indian Encampment by U. U. Lindquist

Indian Encampment by U. U. Lindquist, signature