整个句子是主系表结构.主语I,feel为系动词,与形容词表语sympathy共同构成谓语.
for the people involved是介词短语作状语,involved是过去分词作people的后置定语,修饰和限制people,可以变成一个从句：the people who were involved.
整句话的意思是：我对卷入此事的人们表示同情.