Seven people died after a bus plunged off a bridge on to a riverbank Wednesday in central China's Hunan Province, police said. The bus carrying 52 people crashed through the guardrail and fell off a seven-meter-high bridge on a highway in Shaoyang City at 9:30 a.m., said Tan Ping, a police officer of Hunan Provincial Bureau of Public Security. Four people, including the driver, died at the scene and three others died later in hospital, Xinhua reported. The exact number of injured was still unknown, but Xinhua reporters believe most of the passengers were injured to various degrees. Police are still investigating the cause of the accident.