What killed my Quail

This is my second time raising quail. I just got a batch locally from a guy when they were a few days old. Started them in the brooder as normal. Everything was progressing like normal, they grew fast, feathered up fast, ate, poop, alot, just typical quail. They were the jumbo brown coturnix quail. They were a month old 9-17, and I came home yesterday to find all of them DEAD!!
My previous batch, I had for just about 2 yrs and lost a few to a snake that got in the cage from the top. Have a wire mesh cage, the bottom is 1/4" hardware cloth and the sides are too but the top was large dog fence wire. The snake got in from the top. I did take care of that and Im just wondering what could have happened. Is it possible for a mouse to kill them. There is a dead mouse under the cage and a small opening in the wire for my finger, or a mouse to get into. They were all in the house part in the shavings, and there are feathers loose in the cage area, with small wounds on them.
Just wondering if this has happened before, what can I do to prevent it in the future? Any help or advise would be greatly appreciated!!

I'm sorry to hear about your quail

A mouse wouldn't kill them, I hear rats wouldn't either but rather feed on their food, eggs and droppings... If you have a hole in the cage big enough for a mouse, a snake could have made its way in again like that last time.

If the snake is too small to swallow what it constricts, it won't be able to swallow it hence the dead unharmed looking bodies. I've read on this forum about nightly snakes that kill some adults, can't swallow them so moves on to the smaller ones for a feed.

Are there any parts of the birds that might resemble an attempted snake swallow like crusty messed up feathers?

It sounds like it was a night attack if they were all inside maybe? They may have been panicking and jumping, possibly hitting their heads too :/

Thanks for your response! They did have a wound that very well and most likely could be a snake bite. I will replace the cage screen before I get more quail.