Did I just see the ISS (International Space Station)?

I was watching a plane fly across the sky, but then I noticed something quicker and brighter than it move, so I started watching that. It did not have any lights blinking, and I could tell it was to far away and moving to fast to be a plane, but after a while and very quickly the bright light started to fade until it was nothing. The fading happened in all of 5-10 seconds, and the bright light covered a heck of a lot of the sky that was visible to me. I was wondering what it was? Satellite? Plane?