A feral mamma cat attacked Prince in our backyard once. She didn't do any damage...but she had a hold of his but while he was running towards the house.
I wonder if OP's bengal was the cause of the attack??
If the owners cat was taking a walk with them and happened to wander into the feral cats territory, especially with kittens, it could totally instigate an attack. Cats can be very territorial. I think that the fact that the feral cat went towards the bengal first is a tell tale sign of who the attack was intended for....and once the bengal got away, the feral cat, still in attack mode, lashed out at the next thing closest to it.
Has anyone seen this video...
Cat saves boy from dog attack - video | World news | theguardian.com
That cat was fearless when it took on that big, aggressive dog. He could have looked at the boy as part of his pack/family and protected him when he heard the boys cries.
I watched something on Animal Planet the other night about big cats(tigers, mountain lions etc) catching canine distemper. Apparently it makes them fearless of humans and it has triggered an increase in big cat attacks across the planet. Even if the cats aren't anywhere near a dog, they can catch it from other carriers. They showed videos of some of the big cats who had it...and they were out of their minds. I wonder if it does the same thing to a domestic cat?? If it does, perhaps that is the cause of the cat acting out abnormally.