We would like to express our condolences to those who were affected by the disaster.
「我々も災害に遭われた方に対してお悔やみ申し上げます。」= "We would like to express our condolences to those who were affected by the disaster."
「災害に遭われた方」= "those affected by [the] disaster"
「お悔やみ申し上げます」= "to express condolences", "to express deep sympathy"
もっと丁寧にしたいなら:
"sincerest"や"deepest"を追加できます。この文章で「誠に」という意味です。
例えば、
"We would like to express our sincerest condolences to those who were affected by the disaster."
"We would like to express our deepest condolences to those who were affected by the disaster."
ご参考になれば幸いです。