Teitelbaum - the rebbe, or grand rabbi, of the Satmar Hassidim - died at Mount Sinai Hospital, said community leader Isaac Abraham. He entered the hospital March 30 for treatment of spinal cancer and other ailments.
The Satmars have 120,000 followers worldwide, according to sociologist Samuel Heilman, with large congregations in Brooklyn and the village of Kiryas Joel, 45 miles (70 kilometers) northwest of New York City.
Rabbi Teitelbaum's funeral (Photo: AP)
A Jerusalem resident, affiliated with the ultra-Orthodox-Lithuanian sect, told Ynet that the Satmar Hassidim have witnessed many turmoils in the past two years, following the death of three of the community's senior members.
Thousands of mourners crammed into Teitelbaum's Brooklyn synagogue Monday night waiting for his body to be brought into the main sanctuary. Thousands more congregated outside, and police sent hundreds of officers to control the crowds.
A burial was to immediately follow in Kiryas Joel. Under Jewish law, the dead must be buried as quickly as possible. Teitelbaum took over leadership of the Satmar sect from his uncle, Rabbi Joel Teitelbaum, who died in 1979. He took the formal title of rebbe the following year.
Mayor Michael Bloomberg called Teitelbaum "A gentle soul who carried himself with poise and distinction."
"From the fires of the Holocaust, the grand rebbe and his uncle performed a miracle here in New York by rebuilding their community to match its glory days in Europe," Bloomberg said in a statement.
The Satmars emphasize tradition and adhere to a strict dress code - long skirts for women, long black coats, black hats and long beards for men. Marriages are arranged and married women must keep their heads covered.
Who will succeed him?
The sect takes its name from the town of Satu Mare in what is now Romania. Teitelbaum was born in Siget, in present-day Romania. He escaped Nazi persecution during World War II and came to the U.S. in 1946.
The question of who will succeed him as spiritual leader now looms. Two of his sons, Aaron and Zalmen Teitelbaum, have been feuding over that question.
Members of the sect are so devoted to tradition they even oppose the state of Israel, because they believe that biblically Jewish sovereignty over the ancient Land of Israel can come only with the Messiah.
Teitelbaum's survivors include four sons, two daughters and dozens of grandchildren.
Ilan Marciano contributed to the report