Why did Uri shoot Misha in Milkweed?

In brief, Uri shoots Misha to save him. In Milkweed, Uri is one of Misha’s closest friends. Near the beginning of the novel, he not only rescues the homeless street urchin but gives him an identity, including a name and a plausible life story. Uri himself is Jewish, but Misha is not. Although Uri plays an active role in the Warsaw ghetto uprising, he also takes on the identity of a Nazi soldier. Taking careful aim at Misha, he shoots to injure but not to kill him. Misha is wounded in the ear and loses consciousness. Assuming the boy is dead, the Nazis do not load him onto the train. By wounding his friend, Uri saves him from sure death in a concentration camp.