3 dogs that are aggressive which the owner is physically unable to control, license controls need to a lot more through and should include proof someone is cable of handling and controlling certain dog breeds especially ones that were historically bred for protection.
Seen a similar incident not that long ago but owners were incapable of getting control of the dogs - it was actually one of the dogs which sussed it out and made the other two back off - always found it weird when an animal shows that level of awareness/intelligence - one of our neighbour's cats for instance has several times acted to prevent other cats being run over in the road - even to the point of putting itself at risk.