Was the Leo on Dogs Behaving Badly... if the owners followed that idiots advice and wasn't remotely prepared for a slow maturing (they're not mature adults til nearly three years old) giant breed I can see why that might cause issues.
The self proclaimed experts are out in force I see... one who claims to have trained over 25000 dogs... but would have had to start doing that from birth, without a break, to have acheived anywhere near that number... another claiming to be the UK's Dog Whisperer (none of the people in the industry that I know have heard of him of course, and I work with some of the top people/organisations)..
We have no idea which dog or dogs started anything, we have no idea which dogs bit anyone, we have no idea at this point of anything barring a couple of breeds/types involved.
There are many ways that someone with multiple dogs, on lead, could end up dead, humans are fragile creatures, a blow to the head, a mistaken bite to a major blood vessel (yes, dogs can bite by mistake, aiming for another dog) could all happen very easily.
I hope the real experts (Kendal Shepherd, Jim Crosby etc) are asked, rather than the blow-hard 'self qualified' loud mouths.. but history suggests not sadly.