China promises thorough investigation . Chinese media reports that flaws in railway signalling equipment led to the deadly train crash . China has built the world 's longest high - speed rail network . Thirty - nine people died in the fatal train accident .
Premier promises thorough investigation . State media reports design flaws in railway signal equipment led to the deadly train crash . China has built the world 's longest high-speed rail network . Thirty-nine people died in the weekend train accident .