The term "kar sevak" generally refers to a Hindutva activist, particularly associated with the Ayodhya dispute, and communal violence. "Kar seva" refers to a symbolic religious gathering of kar sevaks.
Kar sevaks are mobilised by Sangh Parivar organisations, particularly the VHP and Bajrang Dal. They can be seen as the footsoldiers of the Sangh Parivar. Many of those killed in the fire on the Sabarmati Express were kar sevaks returning from Ayodhya.