There were 2 strangers at my doorstep?

Ok, so i saw a truck drive near my house and these two strangers came to my doorstep and stayed there for a couple of minutes. and since i didnt know who they were i didnt answer since it was just me and my bro. and then the next moment i heard them trying to open my door but good thing it was locked and they started knocking. after this i still didnt answer. after a couple of minutes standing there they were looking threw my windows and examining the house. just staring and looking at it. then they went back to there car and left. who do you think they were? they seem to be the ages of 40-50?