BAGHDAD, Iraq (CNN) — Tens of thousands converged Friday on the streets of Baghdad to pay final respects to one of Iraq’s top Shiite leaders.Security was tight for the funeral procession of Abdul Aziz al-Hakim, who died in Iran on Wednesday of lung cancer.

The streets leading to the Kadhimiya district were sealed off Friday, and Iraqi air force helicopters hovered overhead.

Sobbing mourners beat their chests and heads, a traditional Shiite way of mourning. They swarmed around the coffin trying to touch it as it was carried into the Kadhimiya shrine, one of Shiite Islam’s holiest.

The funeral procession began earlier Friday at Baghdad International Airport, where Al-Hakim‘s body arrived from Iran. Top Iraqi officials and Western diplomats, including Britain’s ambassador to Iraq, Christopher Prentice, were there, along with Iraqi President Jalal Talabani and Prime Minister Nuri al-Maliki.

The funeral procession then went to the Buratha mosque near Kadhimiya. At Buratha, Friday prayers were led by al-Hakim’s likely successor, his eldest son, Ammar. As people packed the party’s main mosque in the capital, many sat crying as they listened to Ammar al-Hakim talk about his father’s life and his final days in a Tehran, Iran, hospital.Al-Hakim had lived in exile in Iran for more than 20 years, finally returning to Iraq in 2003 after U.S.-led forces toppled Saddam Hussein and his regime.

“It was very emotional for me to meet with my people after Saddam fell,” the Shiite leader told CNN in 2006. “I was longing to see them. My goal in this life is to serve those great people, and I am very proud to be a part of them.”

Iraqi Shiites were suppressed under Hussein’s regime, which favored the country’s minority Sunni Muslims.

After his return, al-Hakim played a central role in shaping Iraq’s future. He urged Iraqis to shun bitter sectarian conflict after Hussein’s fall.

Al-Hakim, who was born in 1950, was considered one of Iraq’s most powerful men. Though he never held a government position, his political bloc won the most seats in the Iraqi parliament in 2005.

President Bush considered him an ally and called him when talks on the Iraqi Constitution stalled. He visited the United States three times during the Bush administration to discuss the situation in Iraq.

Ammar al-Hakim’s address and eulogy on Friday also had political messages. He described how his father, in an unconscious state Monday, signaled his approval for the newly formed mainly Shiite alliance ahead of Iraq’s elections.

The Iranian-backed alliance that was announced Monday included all of Iraq’s top Shiite parties, but excluded al-Maliki’s Dawa party.

In a not-so-subtle hint to the prime minister and his party, Ammar al-Hakim also used the occasion to send a message to parties that did not join the alliance, telling them to reconsider their decision.

Al-Hakim’s party, the Islamic Supreme Council of Iraq, lost much of its popularity in recent years. In January’s provincial elections, it lost much of its control in the south and Baghdad to al-Maliki’s candidates.

The Shiite leader’s death comes at a critical time in Iraq, with fractures in Shiite politics and an uncertain future for his party and for Iraq. Al-Maliki acknowledged as much when he spoke earlier Friday at the Baghdad airport.

Ammar al-Hakim, who has been groomed for years to take over party leadership, is the most likely successor. The senior members of the party, known as its Shura Council, will vote on leadership in the coming days.

Two truck bombs struck separate communities north of Iraq’s capital on Saturday, killing at least 16 people. According to AFP, Saturday’s deadliest attack came at about 8 a.m. local time when a truck bomber attacked a small police station in the remote village of Hamad north of Baghdad, killing at least 12 people, including six police.
Police at a checkpoint attempted to stop the truck, forcing the attacker to change direction and slam into a concrete barrier close to an open air market, they said. The police officials said twelve people were also wounded in the attack.

Memorials planned on Friday in Dearborn as local Shi’ite Muslims mourn the death of Abdul Aziz al-Hakim, an Iraqi religious and political leader who is well-known in metro Detroit’s Shi’ite communities.

Hakim, who once headed Iraq’s biggest political party, visited Michigan in December 2006, speaking at local Lebanese Shi’ite, Iraqi and Chaldean centers after meeting with then President George W. Bush. Hakim, 59, died Wednesday.

“It’s a great loss,” said Imam Husham Al-Husainy, head of the Karbalaa Islamic Education Center in Dearborn. “It’s very sad. People are crying and coming into the center.”

Hundreds are expected to attend the services at the Karbalaa center in Dearborn. And many are watching the funeral services in Iran on satellite TV stations, Al-Husainy said.

Hakim was head of the Supreme Iraqi Islamic Council, formerly known as SCIRI, Supreme Council for Islamic Revolution in Iraq. He hailed from a prominent Shi’ite family of scholars and teachers.

Many of Hakim’s family members were killed by the former regime of Saddam, and he spent his life trying to win freedom for Iraqis, Al-Husainy said.

In metro Detroit, Shi’ites of Iraqi descent admired him, as did Lebanese-American Shi’ites.

In December 2006, Hakim spoke to Shi’ite Muslims at Bint Jebail Cultural Center in Dearborn, a hall named after a town in southern Lebanon largely populated by Shi’ite Muslims.

He told the crowd that Al Qaeda and remnants of the former regime of Saddam Hussein are behind the terrorist violence in Iraq.

“It’s not the Shi’ites doing this,” Hakim said through a translator. “It’s not the Sunnis doing this. It’s the terrorists, the outsiders.”

Hakim also spoke to Chaldeans, Iraqi Catholics, in Southfield and West Bloomfield, and at the Karbalaa Islamic Education Center in Dearborn.

Hakim stressed religious and ethnic unity in his talk, noting that Shi’ites, Sunnis, Arabs, Kurds, Turkomen and Christians have long lived together in Iraq.

The recent violence between the groups is an aberration — not the historical norm — he said.

“We have nothing against each other,” Hakim said. “We go back hundreds of years, living together.”