South African police on Sunday were hunting the perpetrators of two separate shootings that killed 27 people within hours of each other, in stark reminders of the country’s problem with gun violence. Officials were still establishing the motives for the shootings near Johannesburg and Cape Town, but initial investigations suggested one could be a turf war between illegal miners and the other a business rivalry. Violent crime remains rife in South Africa, despite government efforts to curb one of...