Twenty three people were killed and five others were seriously injured after a light truck carrying railway construction workers overturned in northwest China''s Gansu Province Saturday, local authorities said. The truck, with a driver and 27 passengers aboard, overturned in a mountain tunnel in the Manwa township in Lintao county of Dingxi city, China''s News Agency (Xinhua) reported. The tunnel was still under construction as part of a railway that will link the northwestern city of Lanzhou with Chongqing in the southwest. Twenty one workers were killed instantly. Seven others were injured and rushed to the Dingxi Municipal People''s Hospital. An initial investigation shows that a brake failure was to blame for the accident, a spokesman with the local traffic police said. Police continue to investigate the