As memorial events honoring Nelson Mandela take place across South Africa this week, NBC News and WDIV- Local 4 will continue to provide special coverage of the life and legacy of the man who has been called a towering figure in world history.

On Tuesday, NBC Nightly News Anchor Brian Williams will anchor a special report on the NBC broadcast network and NBCNews.com and WDIV- Local 4 beginning at 4am ET as international leaders and dignitaries join members of the public in paying tribute at the national memorial service in Soweto. The U.S. delegation attending this historic international gathering will be led by President Barack Obama, along with former Presidents George W. Bush, Bill Clinton, and Jimmy Carter, and 26 Members of Congress.

Local 4 News Today will bring you local news updates as opportunities are made available Tuesday morning.

Also attending is Congressman John Conyers, Jr (D-Mich). As he departed for South Africa, Rep. Conyers reiterated the message he delivered Thursday evening to the family of Nelson Mandela:

"While we mourn his passage, we know that Madiba's legacy of fighting for freedom and independence will live on."

With 91 heads of state attending, security will be tight.

South African officials won't talk about their security plans -- how many police officers, how many troops, precautions to keep the stadium weapons- and explosives-free.

"But we can assure that all necessary steps have been taken, and that is why the leadership of the world and former leaders of the world have confidence to come to our country at this time to share with us this moment," said Minister in the Presidency Collins Chabane.

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Crews worked overtime Monday to prepare FNB Stadium in Johannesburg for the service.

The stadium, where Mandela delivered his first major speech after his release from prison, can hold some 90,000 people, but that won't be enough to hold the hundreds of thousands clamoring to celebrate Mandela's life.

The government has set up overflow locations at stadiums and other facilities throughout the country.

With private vehicles banned from the area around the stadium, the government pressed buses from around the country into service and stepped up train service to move the crowds.

In addition to Obama and Ban, the presidents of Brazil, Namibia, India, Cuba and South Africa were expected to speak at the service, as were family members, friends and others.

One potential complication: Forecasters predicted potentially heavy rainfall during the event at the open-air stadium.

Security

The event will undoubtedly rival other significant state funerals in recent decades, such as that of former British Prime Minister Winston Churchill in 1965 and the 2008 funeral of Pope John Paul, which attracted some 2 million people to Rome -- among them four kings, five queens, at least 70 presidents and prime ministers and the leaders of 14 other faiths.

At that event, metal detectors and some 15,000 members of security forces stood watch over the event.

Working off plans developed for years in secret, the South African government is using an elite military task force, sniper teams and canine teams to help secure the stadium, CNN's Arwa Damon reported Monday. In addition, helicopters and military jets frequently fly overhead.

"Should anybody, anything dare to disturb or disrupt this period of mourning and finally taking and accompanying the former president to his last resting place, then that person will be dealt with," Brig. Gen. Xolani Mabanga said Monday.

U.S. officials are satisfied with security arrangements.

"We have not heard any concerns," Deputy National Security Adviser Ben Rhodes told reporters aboard Air Force One as the president flew to South Africa.

"The South Africans hosted the World Cup, so they have experience hosting significant crowds and managing events like this," he said, "although clearly this is really a unique event in world history, given the number of leaders coming to pay their respects, as well as the people of South Africa."

Given Mandela's ailing health, the U.S. Secret Service made some arrangements in advance, a Secret Service spokesman said. But work that would usually take months to complete has been done in less than a week, the spokesman said.

"It's a compressed timeline, but there are certain protocols we must have in place for any trip," the spokesman said.