anyone recognise this plot??

[revnev]

I've been trying to remember the name of a book I read when I was young, and I'm hoping that someone here may recognise it and help.

It was about a group of children who go up and find a load of cave paintings, in mountains above their village, and when they come out of the caves, there is a storm. When they make it back to the village, it's empty (I can't remember why, the rest of the inhabitants may have been away on some annual picnic), and there is a bull (I think) rampaging round the village......

Does it ring a bell with anyone??

thanks,

Phil