Calm

Bumped into a friend at the park today dog walking, and before we knew it there were about 8 dogs racing around together. Suddenly there's a lot of growling and barking from Eddie and a little black dog. I called Eddie and he came to me straight away, closely followed by all the others dogs unfortunately, and they started again. All back on leads and playtime came to an abrupt end. I wonder what makes things suddenly turn like that?
We walked round the lake before coming home, it was beautiful and sunny then, but it's snowed 3 times this afternoon, bizarre weather.