What happened was that the shoot of Billa 2 was happening. In one scene Ajith was supposed to throw a bottle on his villain.
Though the bottle was a dummy it was supposed to be handled with care. The bottle was designed not to cause any serious damage injury.
When Ajith threw the bottle on the villain Ajith reportedly hurt his hand resulting in bleeding following which he was immediately administered
first aid and rushed to the hospital. The doctors have advised Ajith complete rest and now he is admitted in the hospital.