Fiery Indian nationalist Bal Thackeray, who founded the right-wing Hindu party Shiv Sena, died on Saturday after suffering cardiac arrest, his doctor said.
Thackeray, 86, has "breathed his last", his physician Jalil Parkar told a huge crowd assembled amid a heavy security presence outside the veteran politician's house in India's financial hub of Mumbai.
Thackeray, regarded as one of India's most divisive politicians, had been put on a ventilator earlier in the week after his health deteriorated sharply, and Parkar said attempts to revive him when he suffered a cardiac arrest failed.
Authorities placed thousands of extra police on the streets to prevent unrest following the death of the politician, who had been widely accused of having stoked ethnic and religious violence in the past.
News of his failing health had drawn large crowds to his residence, putting Mumbai on high alert amid concern that their grief could turn to anger.
Supporters gathered there sobbed into their handkerchiefs after hearing the news of the death of Thackeray, one of the best-known figures in the Maharashtra state and its capital, which his party renamed from Bombay to Mumbai.
The funeral rites for the founder and president of the Shiv Sena or the Army of Shivaji -- the Maratha king who battled against the Muslim Mughal empire -- were due to be held on Sunday.
A massive procession was planned through the streets of Mumbai for Thackeray, known for his charismatic speaking skills and nicknamed "The Tiger" because of his fearlessness and readiness to take on any opponent.
Tributes poured in for the politician.
"He was an iron man, he spoke in the language of the masses. It worked very well because he connected with them at the very basic level. He gave them hope," Shobhaa De, novelist and a popular columnist, told India's CNN-IBN network.
Under Thackeray's lead, the Shiv Sena had long fought to protect local Marathi-speaking "sons of the soil" from migrant workers.
"He was a consummate communicator whose stature in the politics of Maharashtra was unique," said the office of Congress Prime Minister Manmohan Singh on social networking site Twitter.
The party, which has controlled Mumbai's city council since the mid-1990s, is a staunch ally of the Hindu nationalist and main opposition Bharatiya Janata Party (BJP).
The BJP announced it was cancelling its attendance at a dinner to be held by Prime Minister Manmohan Singh on Saturday night to show respect for Thackeray.
As rumours about his condition swirled earlier in the week, roads were unusually quiet and numerous shops shut, especially in strongholds of the Shiv Sena, a party associated with intimidation and violence in the past.
Thackeray's son Uddhav, the Shiv Sena executive president, had appealed to the party's supporters to stay calm.
Testament to Thackeray's enduring clout were not only the crowds of loyalists but a stream of high-profile visitors to his home while he lay on his deathbed, including politicians, businessmen and film stars.
Bollywood veteran Amitabh Bachchan and his actor son Abhishek were among those to visit on Wednesday night, when they suffered minor injuries in the rowdy crowds.
The elder Bachchan spoke fondly in memory of Thackeray on Twitter, saying it was "difficult to imagine that he has left us!"
Thackeray had been admitted to hospital in July with breathing problems and in October his ill-health prevented him from attending a Shiv Sena rally, which he instead addressed by video link.