2008 F150 5.4 power issue?
 

I have a 2008 F150 5.4 Lariat and it was driving fine. I was in a parking lot driving at 5mph or so when I heard a thumping noise and then no power. I noticed the truck jumped into 4L on its own. It had no power and I could barley make it into a parking spot. I tried to change the on dash switch back to 2 wheel drive with no success. After parking it I noticed some fluids under the truck. Any clue what could have happened. Thinking it may be a transfer case issue but not sure.