While Vijay was wearing a life jacket inside a camouflaged jacket, Anil and Uday were just wearing pants.
All the three had rehearsed the scene before the shoot.
In the footage, Uday and Anil are seen trying hard to swim in the lake as they scream for help but before people could understand what was happening, the two were immersed in the water.
Before the actors went for the shoot, Uday had told a local press he was not a good swimmer and was "scared as he had not done a stunt like this before."
The video from the shooting location shows people on the shore shouting at a rescue boat to rush towards the drowning stuntmen, but it could not move due to a technical fault. It is also alleged that there were no expert divers or swimmers on the spot.
Locals say that the reservoir is extremely dangerous as there are 30-40 feet of silt below 15-20 feet of water. The lake is also full of abandoned fishing nets at the spot.
"The rescue operations are still going on. We will be booking a case of negligence against those responsible and also inquire into all aspects of the case," said Dr. Chandra Gupt, Ramanagara Superintendent of Police.
"We need to check whether all adequate measures and permissions were taken or not."
The Bengaluru Water Supply and Sewage Board (BWSSB) has clarified that they allowed the movie crew to shoot near the lake but had given no permission to fly a helicopter or chopper or even jump into the reservoir.
RIP.Two stuntmen drown whilst filming a stunt from a chopper in a Kannada film. When VFX facilities available,then why endanger human lives? pic.twitter.com/HvPjlrLr8f
The video footage from the spot went viral as there were onlookers who had come to see the shooting. Entertainment reporters were also invited by film's director Nagashekhar and producer Sundar Gowdru. The action scene was being choreographed by action choreographer Ravi Verma.
Anil, a resident of Banashankari, is survived with two children whereas Uday was unmarried. Both of them were known as the best stunt artists in the South Indian film industry for a long time.