The actor, who is known as "Powerstar" because of his action roles in Kannada-language films, was admitted to hospital Friday morning suffering from chest pains. He died shortly thereafter.
Prime Minister Narendra Modi led the tributes. He tweeted that a "cruel twist in fate" had taken away a talented and prolific actor. His amazing personality and his work will be remembered fondly by the next generation.
Basavaraj S. Bhommai, Karnataka chief Minister, stated that Rajkumar was the state’s "most loved superstar... It's a huge personal loss that is difficult to accept."
Fearing violence from his fans, authorities increased security around his house. Some of his fans could be seen running after the ambulance that was carrying his body.
An employee said that Tata Consultancy Services in India, India's largest IT services company, sent an advisory to its employees asking them to return home early. According to the news agency, KPMG, an accounting firm, asked employees to return home. His admirers were also crying and hugging him.
It is extremely difficult to have lost him. He was an icon in Kannada cinema and is still remembered. It is very difficult," Sandeep, a bereaved fan, said to AFP.
Puneeth Rajkumar was the son of Rajkumar and was about to start work on a new movie.
He made a name for his self as a child actor and starred in more than 30 films. His first action-comedy film, "Appu", was one of the most popular. Reuters reported that he also hosted the local edition of "Who Wants To Be a Millionaire."
Bollywood in Hindi is India's largest film industry, but it also produces hundreds of films every year in its 21 official languages.
It feels like I have lost my younger brother. His family is in my thoughts and prayers.
Chiranjeevi was a star in Telugu-language film and said Rajkumar's death was a "huge tragedy" for the Kannada film industry and the Indian film fraternity.
Rajkumar's wife Ashwini Revanth is still living and has two children.