BEIJING - A powerful explosion ripped through a building in a northern Chinese city on Monday, killing 10 people and injuring more than 150. Media reports said the blast in Yulin, which destroyed or damaged nearby buildings including a hospital, may have been caused by explosives illegally stored in the building. The official Xinhua news agency said dozens of firefighters were sent to the scene in Shaanxi province, and rescuers were hunting for survivors who may be trapped in the rubble.