MORE than 500 Metro passengers had to be led to safety yesterday after an electrical fault caused a Line 2 train to become stranded inside a tunnel.

The incident happened about 11:30am when the pantograph atop the train malfunctioned as it was approaching Jinke Road station, operator Shanghai Shentong Metro Group said.

Though no one was injured, sparks and smoke were seen coming from outside the train as parts of the pantograph fell to the ground, the company said.