People were evacuated immediately. No one was injured, an official said. "A minor smoke was reported from the air-conditioning vent of the last coach of a metro train at Rajiv Chowk platform heading towards Badli. As a precautionary measure, the train was evacuated at the station itself and passengers were accommodated in the next train," a Delhi Metro Rail Corporation (DMRC) official said.
The train has been sent to the DMRC depot to check for any fault, the official said, adding metro service has been restored on the Yellow Line.
According to eyewitnesses, sparks first appeared when the train entered Central Secretariat station. The sparks reappeared after it left Patel Chowk station and headed toward Rajiv Chowk, they said.
Passengers started tweeting, shaken by the explosion-like noise that accompanied the spark and smoke. "Witnessed two explosions at Rajiv Chowk 15 mins back. What's happening? And again when it reached Rajiv Chowk," a person wrote on Twitter.
"Something's not right at #RajivChowk. 2 explosions in electric box back to back," another person tweeted. Commuters at Rajiv Chowk metro station say the DMRC does not have a social media outlet to update commuters on events affecting metro services.
In December 2016, thick smoke engulfed a metro coach following sparks in its air-conditioning system, forcing the evacuation of a train full of panicking passengers at Patel Chowk station.
The 48-kilometre-long Yellow Line or Line II connects Huda City Centre in Gurugram and Samaypur Badli in north Delhi.