Gandhi went to Shakur Basti in west Delhi with Delhi unit Congress president Ajay Maken after the demolition of about 500 hutments by railway authorities left hundreds out in the open in the winter chill.
An infant also died on Saturday although officials insisted that the death had nothing to do with the razing.
Gandhi told the affected families: "We will try to help you... We will fight for you and won't let this gross injustice happen to you. We will raise the issue in parliament."
Meanwhile, Railway Minister Suresh Prabhu defended the demolition and said the child died even before the operation began.
Prabhu told the Lok Sabha: "Despite repeated notices, the encroachers did not vacate the place. The child had died before the demolition drive."
The demolition has triggered a blame game between the Delhi government and railways.
The railways say the hutment dwellers were occupying railway land illegally and that the area needed to be cleared to lay new railway lines.
Maken promised to provide relief to those left homeless.
"We will do as much relief work as possible and fight for justice," said Maken, adding such a thing did not happen when the Congress governed Delhi.
Gandhi and Maken criticised both the central and Delhi governments for the demolition.