Babysitting

Brittany • 25, married, one child and pregnant with my second
I saw a post on facebook of a mother who left her 9 year old to watch a 3 month old and a 1 year old child. In the end the 3 month old was found died when the mother returned home. Now the story of the mother and where she went... From what camras show and what she told police was she left her home around 1am and returned around 2:30am from the bar and found her 3 month olds head in a plastic bag. 
So my question to y'all is what's y'all's input on this, would you or do you let your oldest child watch the younger kids, and how young is to young to be watching kids??? 
My opinion is that I been watching kids since I was 9 even babies.. I watched them while their parents went out clubbing too.. But the kids was always in bed already or I would have to put them to bed after an hour or so. To me since I have babysat at a young age this is a freak accident cuz the mother wasn't gone but an hour and a half. Plus we don't know the whole story.. Maybe she did have the kids in bed before she left and just asked the oldest to tend to the babies if they cry.. Who knows..
P.s 
  My son is 4 and I just now started getting babysitters.. Usually my friends.