Cat behaving aggressively

Question
Recently, our indoor cat Sigmund, whom we rescued from our local animal shelter, got outside. When my girlfriend picked him up to bring him in, he acted normal. However, after a few minutes he became really aggressive, and attacked her leg. He tore her up pretty good. I got home, and she was outside telling me what had happened. I came in, and he did the same thing to me! She is the major cat lover, and needless to say, she is disappointed in his behavior. He is usually very loving. I however am not a tremendous cat person, and it made me very angry. We checked on him later, and he was showing the same signs. Then we checked on him a little later, and he seems somewhat normal. What would have made him act like this? I have two sons, and my girlfriend has a niece that comes to visit often. We are concerned he might act this way again. We don't want them to be afraid. Oddly enough, he is laying with his head on the keyboard right now. Any answers, or tips you might have, would be greatly appreciated. Thank you!

Answer
Hi John,

Don't worry about Sigmund. He is acting along normal lines. He was scared out of his mind. When you came to get him he was in a very defensive mode. He most likely didn't recognize you as who you were. Just as someone who he had to protect himself against. He was in a very basic me cat against all else survival mode. This is why he attacked you two.  Keeping him in a quiet place at home was the best thing you could have done. He needs a little time to calm down and realize he is home and safe. He will be back to normal soon.  Give him some extra treats and quiet loving with you two. He will be fine. Good luck.

Ciao, Karen