I often witness them getting very angry. The collective noun for crows is a murder! For good reason. They are extremely intelligent and they look out for each other.

Sorry you were attacked.

Crows are very territorial and the attacking birds may have been protecting a nearby nest.

I have been swarmed upon by a crow as well.

I have a crow couple in the nieghborhood - they are the boss of the street. When they see me outside they crow out to eveyone and the squirrels come running along with a blue jay. I put out peanuts for them (unsalted). I think one time they got into a fight with two hawks that go sit in a very high tree.

I have a crow that came into my garage one day, while I was cleaning. i gave him a few nuts and he returned every day. His mate always stayed up on the phone wire. If I walked my dog before putting out nuts, he would fly down and very gently hit me with his feet. When he stopped showing up, I was worried and saddened... Only to find out that he was eating his preferred meals across the street! He even touches down on the children there! :)