Disclaimer: I do not own Avatar.
Katara,
Something horrible has happened. It's about Shuchun's parents. The renegades made their move. They attacked Shuchun's hometown. They raised everything to the ground. A few survivors were found and there's evidence that others escaped, but we found so many others that didn't make it out.
It's my fault. I allowed this to happen. All of those people. Gen and Ai. Everyone. I need you. Shuchun needs you. Please come as soon as you can.
Zuko