How is this possible?

When I read a story like this, I just want to sob.

Police shoot man as he beats toddler

TURLOCK, California (AP) -- Police killed a 27-year-old man as he kicked, punched and stomped a toddler to death despite other people's attempts to stop him on a dark, country road, authorities said.

http://www.cnn.com/2008/CRIME/06/16/toddler.killed.ap/index.html