Vieira de Mello, the 55-year-old Brazilian diplomat had served in the United Nation since 1969 in some of the world’s most sensitive areas including East Timor, Yugoslavia, Cambodia and Bangladesh.

Bernard Kouchner, co-founder of Doctors Without Borders, said of de Mello “Sergio is dead and for us he died as an activist, not as an international bureaucrat. He was a human rights and peace activist, a just man who fought against all forms of extremism.” In Brazil President Lula declared three days of national mourning in honor of de Mello.

Among the other dead was American Rick Hooper, who worked in the department of political affairs and Canadian Chris Klein-Beckman, who served as program coordinator for UNICEF.

Next door to the UN headquarters is Baghdad’s spinal cord hospital which also suffered damage from the blast. The hospital had to be evacuated after the ceiling fell in. At least eight patients, many of whom already couldn’t walk, were injured.

Today UN Secretary General Kofi Annan said the will stay in Iraq despite yesterday’s “senseless” attack.