A high-speed train lost power in China on Sunday morning coming to a halt after sparks erupted from the roof of one its cars.

A Chinese newspaper reported that the train lost power while traveling from Xian to Zhengzhou and was subsequently replaced with another train.

However, the same phenomenon occurred to the replacement, which was also swapped out. Overall, the incidents delayed the operation of three high-speed trains.

Chinese railway authorities investigating the case believe the sparks were caused by thick dust on the electric devices of the trains, which had built up from serious smog near Xian at that time.