BEIJING – Weekend violence in China’s restive Xinjiang region left as many as 15 people dead, including three killed during or after a bombing attack Sunday afternoon and four attackers shot dead an hour later by Chinese security forces, according to official news agency accounts and residents reached by telephone. The Sunday violence follows an incident reported late Saturday, when two bombs exploded, and two assailants reportedly hijacked a truck, stabbing the driver and ramming the vehicle into a crowd of pedestrians, killing seven people and injuring 22. The crowd reportedly killed one of the hijackers. The violence occurred in...