These deaths are needless. This is the first link to the initial call of the accident. There will be more explanation coming...
Most likely he was working on his own with no training or knowledge of the potential hazards he was involved with. That is just a guess but lets see how it plays out.
Here are the various links as the story breaks...
http://latimesblogs.latimes.com/lanow/2011/02/man-killed-in-studio-city-when-trench-collapses.html
http://www.sfgate.com/cgi-bin/article.cgi?f=/n/a/2011/02/08/state/n161330S36.DTL
http://bhcourier.com/article/Local_News/Local_News/Construction_Worker_Killed_Near_Mulholland_Drive_As_Trench_Collapses/74553
