What would you do?

Have you seen this show? It's a show on ABC on how people react in certain situations. This past Tuesday they had a segment on how people react to a baby crying all alone in a hot car. Sadly a lot of people just walked on by. Tonight my sister, Brinae, and I were faced with this. We went to Sears and as we walked in we saw an SUV. I don't know what kind it was, but the trunk was pretty small. It looked like maybe the people were traveling because the trunk was stacked with stuff. I probably wouldn't have paid any attention, but the dogs in the backseat were barking. I did a double take as we walked by. A woman was standing at the back with the window part (not the whole trunk door) open and there was a baby in an infant seat in the trunk. It just looked weird. There were two dogs on the backseat, one was fairly large. So we go int he store and I ran back out to the car about 15 minutes later. The woman is in the passenger seat and the trunk window is closed. I looked to see if I could see the car seat in the backseat, but it wasn't there. It was in the trunk. I don't know if the baby was in the lady's lap or not. It just looked really odd. So when I went back in I used the phone (my cell was home with Bry) and called the police. We left and these people were pulling out. I pulled out behind them and sure enough, car seat is still in the back window. So this time I double checked the lisence plate state and number, saw the shopping center parking lot they went to (I did try to get them to pull over by honking and flashing my lights, but they didn't. I really have no clue what I thought I was going to say to them). So I called the police again and told them where the people went and gave them the license plate info. I don't know what happened, but I hope the police found them. Obviously I didn't call because I wanted them to get in trouble, I was jsut seriously concerned for the baby. So, what would you do?