Will Keeps was a 15-year-old member of a Chicago gang when he witnessed rival members kill his friend. He escaped the streets and moved to Iowa to help other young people from troubled backgrounds.

Now, Keeps is hospitalized and in serious condition following just the sort of violence he has devoted his life to stopping: a shooting that killed two teenagers at the Starts Right Here education program he founded in Des Moines. Keeps was also shot in Monday's attack, which police say was gang-related, and underwent surgery.

Keeps, 49, is a rapper and activist whose given name is William Holmes. H...