What is the saddest thing you have ever seen?

Today I was coming home and got stopped at a red light, turning left (entering a residential area). I saw a little puppy running towards the intersection with a girl running after it (presumably hers) and it starts to cross, with cars going about 45 mph - the light was green both ways. I thought "oh no this is not going to end well". The puppy made it to the median, but took a few more steps and BAM. Got ran over twice, right in front of me. Brutal sight. My light turned green and there was this little girl, on her knees, hands covering her face, crying.