The tragedy happened in Kochi, a major port city in the southern state of Kerala.
The audience scrambled to find shelter after the festival was interrupted by rain, Sky News reported.
State health minister Veena George confirmed that four people - two boys and two girls - were found dead.
George said that many people got injured in the rush, amid reports suggesting at least 60 people have been hurt.
She said 56 people were taken to hospital for treatment, with five girls in a critical condition in an intensive care unit.
Seventeen children have now been discharged, Ms George added.
More than 100 ambulances have been deployed to the scene.
MP/PR