Strange "scraping" noise from under car?

I have a 1987 Chevy Astro Van and recently there has been a noise coming from under the car. It started a few days ago and seemed like it was only happening while driving and it wasn't very loud. However this morning when pulling into work it was much louder & even continued after I had stopped. I shut off the engine for a few minutes & turned it back on and the noise continued. I can only explain it as a scraping noise, but that may not be correct. The noise is hard to explain. My power steering hasn't been working for a couple weeks so I'm not sure if maybe it is related to that? I have put in fluid last week but it slowly leaked out & I have been dealing with driving with no power steering, but it is now making this noise.