No good deed goes unpunished?

What is the right thing to do when you see someone suffering on the street? The other day on my drive home through downtown Dallas I saw a man lying spread-eagled on the street. I called 911 and reported the situation. I was pulling up to my driveway and got a call from the Fire Department ambulance that they couldn't find the man and could I return and find him...OK, I decided I had started this and should see it through. I went back and found him, now he was leaning up on a dumpster a few feet from where I said he was. The ambulance was nowhere...and I called them back. 5 minutes later they drove up, took a look at him and then started questioning me. Did I know him? What happened to him? And finally, "Maam, he's just drunk and needs to sleep it off." I started driving off, then was curious to know what exactly they were going to do, if anything. They saw me watching them and began to question me again, this time with some attitude. I get the feeling they just wished I had driven by and not bothered noticing the man who was obviously in bad shape, and now were annoyed that I was "forcing" them to attend to him. My question again is, What is the right thing to do when you see someone suffering on the street?