what type of people were christians Xs body guards in the book number of stars

In the book "Number the Stars" by Lois Lowry, the type of people who were Christians' bodyguards were resistance fighters who were opposed to the Nazi occupation of Denmark during World War II. These resistance fighters were willing to risk their lives in order to protect the Jewish characters in the story, including the Jewish girl named Ellen who was being hidden by the Johansen family.