This must be an older story.
This article has the (male) cop back on duty as of yesterday.
http://www.nvdaily.com/news/2013/05/officer-back-on-duty-after-gun-discharge-on-school-bus.php
“Lauren Cummings, police community relations specialist, said investigators have determined the gun fired accidentally through no fault of the officer.”
Yep.
I have the Ruger 38 special and a Colt 38 and their holsters cover the trigger housing. And, I have a fanny pack that looks like a purse and the Ruger fits in there just swell in the space made for it so it's covered completely - no way to pull the trigger accidently.