ABS light on and left front tire brake very hot

I have a 2011 Ford F-53 chassis. While driving today my ABS light came on and when I started to stop I could feel a "thud/thump" don't really know how to describe it. It did it again when I took off. Drove until it was safe to pull over (about two blocks). When I got out of the coach I noticed a burning smell and saw some black fluid (it wasn't splattered just looked like it ran down the rim) on the rim of the tire. Not alot of fluid and the brake was very hot. Had it towed to a shop am waiting for the results. Has anyone experienced this before? If so what are some of the possibilities?

Thanks for all the feedback. Good news and bad news. Brake pads o.k. - calipers released on their own o.k. rotors - o.k. seals needed to be replaced and ABS sensors fried. So not as bad as it could have been. Thank goodness pulled over as soon as I sensed trouble saved me lots of $$$$$$. Only problem was the repair shop wasn't exactly what caused the problem.