An oil tank exploded and caught fire in east China\'s Shandong Province on Friday, leaving one person seriously injured and another one missing, local authorities said.The blast happened around 9 a.m. in a tank storage area in an industrial zone in Gaoliu Township in the city of Qingzhou, Xinhua quoted a municipal firefighter as saying.More than ten fire trucks have been sent to the scene to put out the fire. Firefighters have used high-pressure water jets to cool down seven nearby tanks that contain crude oil in order to prevent subsequent explosions.The cause of the blast is under investigation.