"News of the collapse of a flyover in Kolkata extremely tragic. I hope rescue and relief operations reach those trapped and injured at the earliest," Gandhi tweeted.
"My heart goes out to the people who have lost loved ones in this tragedy," he said in another tweet.
Fourteen people were killed when a portion of the flyover under construction collapsed. At least 17 others were injured and taken to hospital, said West Bengal Chief Minister Mamata Banerjee.