Sounds like the dog might have escaped & is scared.. If the dog was really angry it would have done more then what it did.. It sounded like it wasn't sure what to do.

Something similar happened to a neighbour's dog back home. They were new & everyone knew the Rottie was semi protective, but not a wild beast. THey also knew the dog was always in teh house or in the fenced yard. One day the dog was in the front yard, barking & snapping at people who tried to come near the property or the sidewalk. Neighbours also saw the dog trying to get back into the house from the window he fell from (it wasn't high at all). The police showed up & made a no-walking barrier. The neighbours made it VERY clear the dog was just scared & DO NOT HURT HIM. The police noticed this too & didn't harm him, when the dog came barking up to people the police shouted at him to go home & he would run further into the yard keeping away.. poor thing was soooo scared & confused. Luckly he got back through the window & the police boarded him in.

After that several neighbours visited the new neighbour to let them know what happened & they were worried not so nice police would show up next time & just kill the poor dog. So the neighbours got to know the dog & became his friend, so if something happened again, they could just call him over & lock him up in their yard, or inside their home so he would be safe.

I'm hoping this is a similar case & the poor dog was scared & confused after escaping from its home.