Seven gunmen wearing ski masks entered a hospital in a northern Mexican state capital Wednesday and killed a lawman who was recovering from gunshot wounds, as well as two men accompanying him, investigators said. The assailants arrived at the Clinica del Centro hospital in Chihuahua City, the capital of the U.S.-Mexico border state of the same name, just after 1 a.m. After subduing security guards and covering surveillance cameras, the group moved into the room of federal agent Victor Estrada, said Rene Medrano, a spokesman for Chihuahua state attorney general's office. Authorities have made no arrests and refused to discuss...