Cairo (CNN) -- Thousands of people flooded into Cairo's Abbasiya Cathedral Tuesday to say a final farewell to Pope Shenouda III, the spiritual leader of Egypt's Coptic Christians for more than four decades.
Shenouda III died Saturday at the age of 88.
His successor's name will be chosen by a blindfolded child from among three finalists chosen by community leaders -- a process that could take months.
The funeral could bring millions of Christians onto the streets of Egypt at a time when tensions with the Muslim majority are high.
Egypt's Christian minority has been the target of a number of high-profile attacks in the past several years.
The bombing of a major church in Alexandria in January 2011 left at least 21 people dead, and at least 25 Coptic Christians and their supporters were killed in clashes with the army in October. That incident was the bloodiest in Egypt since its revolution in February.
There has also been tragedy linked to the death of Shenouda.
Three people died Sunday in a stampede at the overcrowded cathedral where people were paying their last respects. More than 50 people were injured in the crush, a health official said.
Most of the injured suffered from lack of oxygen and low blood pressure, according to Deputy Health Minister Hisham Sheeha.
Christians are a very small minority in Egypt, although the Coptic Orthodox Church is the largest Christian church in the Middle East, according the Coptic Orthodox Church Centre in Stevenage, England.
The U.S. State Department estimates that Egypt is roughly 9% Coptic Christian, but the Pew Forum on Religion & Public Life, which released a report on the global Christian population last year, says it is probably closer to 5%.
Egypt did not release the number of Christians in its 2006 census, the think tank said.
The leader of the Coptic Christian community since 1971, Shenouda was in poor health off and on for many years. He traveled to the United States to undergo medical tests last year.
He died of renal failure "due to the diabetes he endured for years," said Sheif Doss, head of the Egyptian General Coptic Association. The pope also had lung cancer, which spread to the rest of his body, Doss said.
"The funeral... is a historical event and 2 million people are expected to attend the prayers. I don't expect violence though," Doss said.
Egypt's Supreme Council announced Sunday three days of mourning for the Coptic Christian community.
Shenouda will be buried later Tuesday at Emba Bishoy monastery in Wadi Natroun, northwest of Egypt's capital, said Markus Askuf, spokesman for the Coptic Church. The area is home to some of the world's earliest Christian monasteries.
Shenouda, a journalist in his youth, was once sentenced to spend four years in Wadi Natroun by the late president Anwar Al-Sadat.
In addition to millions of followers in Egypt, the Coptic church has adherents in Europe, Canada, the United States, Kenya, Zimbabwe, Namibia and South Africa.
U.S. President Barack Obama and his wife offered their condolences Saturday after news of Shenouda's death spread, saying he will be remembered as "a man of deep faith, a leader of a great faith, and an advocate for unity and reconciliation."
"His commitment to Egypt's national unity is also a testament to what can be accomplished when people of all religions and creeds work together," the Obamas said.
When a Coptic pope dies, all 150 bishops of the church's Holy Council appoint an acting patriarch until a vote is conducted for a successor, Doss said. Thousands of bishops, priests and monks are eligible to vote.
The most senior bishop usually takes the role of acting patriarch. In this case, that would be Bishop Michael of Asiut. If he declines, Bishop Bakhamious of Behira is next in line, Doss said.
Journalist Mohamed Fadel Fahmy contributed to this report.