1997 Chrysler Concorde Something that smells & burns co

I had recently purchased a 1997 Chrysler Concorde & I had all of the fluids changed. When I got home I noticed a large brownish puddle in the front of my car. I was told that the power steering has a leak, but as I went for another drive, I noticed a strong smell coming from my car & then all of a sudden I saw smoke coming from my back seat. When I lifted up the back seat right in the middle it was smoldering with a strong smell & smoke. What could have caused that?