A total of 21 people were confirmed dead after a mid-size bus plunged into a river Saturday night in southwest China's Guizhou Province, local authorities said.

Three people were also injured when the bus veered off a mountain road and plunged nearly 100 meters onto a dry riverbed in Nayong County, Bijie City, according to rescue headquarters at the site.

An initial investigation suggested that the bus illegally drove onto a mountain road intended only for small vehicles.