We love photography, but we admit that it can be hazardous when your focus is on the picture.
In a crowd leave one hand on your camera at all times and bring it to the front. But it should be there anyway because you should be shooting.
Be aware of your surroundings when shooting in a populated place. This is a most vulnerable time because you are only thinking about the photo. It's how photographers fall into swimming pools, off a cliff, or even walk into traffic. Have someone walking behind you or have them hold onto your belt.