Tamil Nadu DGP G Venkataraman explained the Karur rally stampede. He cited actor-politician Vijay's delayed arrival as the cause. A large crowd waited hours in the sun without food or water. Vijay's party Twitter handle announced an earlier arrival time. This led to an unexpected surge of nearly 27,000 people. Police deployment was for 20,000, not the actual turnout.

Source: Karur stampede: Crowd swelled with no food, water due to Vijay’s delayed arrival