Officers stand watch at the intersection of West North Avenue and Pennsylvania Avenue as protesters walk for Freddie Gray in Baltimore in April. Gray died from spinal injuries about a week after he was arrested and transported in a police van. Jabin Botsford/The Washington Post/Getty Images hide caption

itoggle caption Jabin Botsford/The Washington Post/Getty Images

A Maryland state trooper stands guard near a CVS pharmacy that was destroyed during rioting in Baltimore this week. Andrew Burton/Getty Images hide caption

itoggle caption Andrew Burton/Getty Images

Robert Bates (left), a Tulsa County, Okla., reserve deputy, leaves his arraignment Tuesday with his attorney. Bates fatally shot a suspect who was pinned down by officers, raising alarms about volunteer police officers who wear badges and carry guns. Sue Ogrocki/AP hide caption

itoggle caption Sue Ogrocki/AP

Rick Ector trains new gun owners at a range just outside of Detroit. He supports more African-Americans getting permits to carry concealed weapons. Martin Kaste/NPR hide caption

itoggle caption Martin Kaste/NPR