Security was tightened in South Africa’s Kruger National Park nature reserve after two tourists were found killed there, authorities said on Sunday. The two South African victims, a 71-year-old man and a woman whose age was not disclosed, failed to return to their lodge on Wednesday evening, prompting a search operation. Other tourists eventually found them in a river on Friday afternoon. Police said the man had stab wounds and the woman’s body was bruised. Their car was missing. South Africa...