Bal Thackeray was suffering from multiple ailments. Official announcements is expected to be made by his family members shortly.
Doctor Jaleel Parkar, who was the in-charge of the medical team, said, "Bal Thackeray had cardiac arrest and we could not revive him despite efforts."
Shiv Sena party leaders asked its Sainiks (workers) to maintain calm and peace in Mumbai which has come to an standstill after getting the news of Bal Thackeray's demise.
Security has been beefed up around the Thackerays' residence - Matoshree where all Shiv Sena and political party leaders gathered to show their last tribute to their leader.
Funeral procession will begin at 10 am on Sunday from Matoshree. The cremation is expected to be taken place at 3:00 PM.