At least 13 people, including seven school children, were killed and more than 10 others injured in a major road mishap in the southern Indian state of Kerala on Friday, a senior police official said.\"The mishap happened when a private bus in which the victims were travelling hit a tree and then plunged into a deep gorge at Pernithalmanna in the state\'s Malappuram district, after the driver lost control of the speeding vehicle while overtaking another bus,\" he said on condition of anonymity.While 13 people, including seven school children returning home after an examination, died on the spot, all those injured have been admitted to a local hospital where the condition of some are said to be serious, the official said, adding that the death toll could go up.\"The government will ensure best treatment for all the injured, \" state Transport Minister Aryadan Ahmed told the media.