In Colorado, where more people die from gunshots than car crashes, the victims have a profound effect on the physicians who treat them. For some of the doctors on the front lines, the experiences lead to a strong opposition to guns, questions about gun laws and even activism. Dr. Chris Colwell, an emergency department physician in Denver, says he sees gun-violence victims on a weekly basis. And when those cases are fatal, they are hard to forget. "These are the injuries that the [patients] will come in, and they'll look at me, and they'll talk to me, and then they'll die," says Colwell, who's been at Denver Health, the city's biggest public hospital, for 20 years.