"Shocked & saddened by collapse of under-construction flyover in Kolkata. Took stock of the situation & rescue operations," Modi, who is in the US on an official visit, tweeted.
"My thoughts are with the families of those who lost their lives in Kolkata. May the injured recover at the earliest," he added in another tweet.
Sources said the Prime Minister is in touch with officials in Delhi and has instructed all possible assistance to be extended by Army and NDRF in rescue and relief operations.