(CNN) -- World leaders reacted with sadness, shock and condemnation Thursday to the assassination of former Pakistan Prime Minister Benazir Bhutto, some expressing concern about the nation's democratic process:
Bhutto (center) waves to supporters at a campaign rally minutes before she was assassinated.
Pakistani President Pervez Musharraf
"At this unfortunate incident, in honor of Madam Benazir Bhutto, I am declaring three days of mourning. Our flags will fly at half mast.
"This is the work of those terrorists with whom we are engaged in war. I have been saying that the nation faces the greatest threats from these terrorists. Today after this tragic incident, I want to express my firm resolve. I express my resolve that -- and I also seek solidarity from the nation and cooperation and help -- we will not rest until we eliminate these terrorists and root them out."
Pakistani Ambassador to U.S. Mahmud Ali Durrani
"I think it's a national tragedy and a day of national mourning for Pakistan, and we have lost one of our important, very important and, I would stress, liberal leaders."
Afghan President Hamid Karzai
Karzai met with Bhutto Thursday morning during a visit to Pakistan.
"I found her to be a very, very brave woman with a clear vision for her own country, for Afghanistan and for the region.
"We in Afghanistan condemn this act of cowardice and immense brutality in the strongest possible terms. She sacrificed her life for the sake of Pakistan and for the sake of this region."
U.N. Secretary-General Ban Ki-moon
"I am shocked and outraged by the assassination of Mrs. Benazir Bhutto, the leader of the Pakistan People's Party and former prime minister. This represents an assault on stability in Pakistan and its democratic processes. I strongly condemn this heinous crime and call for the perpetrators to be brought to justice as soon as possible. I convey my heartfelt condolences to Mrs. Bhutto's family, her colleagues and to the people of Pakistan. While strongly urging for calm and restraint to be maintained at this difficult time, I call on all Pakistanis to work together for peace and national unity."
Saudi King Abdullah, in a cable sent to Musharraf
"We pray to Almighty God to bestow the deceased martyr with forgiveness and mercy and to allow her to reside in paradise and to bestow condolences and patience upon her family and relatives. We also pray that Almighty God bestow dear Pakistan and its noble people with pride, power, and triumph over the gangs of evil and darkness."
Jose Manuel Barroso, president of the European Commission
"The European Commission condemns this callous terrorist attack perpetrated less than two weeks ahead of election day in the strongest terms. This is an attack against democracy and against Pakistan.
"We send our condolences to the family of Mrs. Bhutto and to the family of the other victims. We hope that Pakistan will remain firmly on track for a return to democratic civilian rule."
Statement on behalf of Israeli President Shimon Peres
"The assassination of Benazir Bhutto is a very shocking/horrifying murder. She was a courageous woman and a charismatic leader that did not hide her views, and served her people bravely and with rare competence."
Peres said "he met her twice and said that she was very interested in what was going on in Israel, and expressed hope to come and visit when she is elected. Peres added that in his eyes, she will be remembered as a brave leader who had fought for peace in the world as well as for peace in her country."
Israeli Foreign Minister Tzipi Livni
"We convey our condolences to the people of Pakistan and to the families of the victims. Benazir Bhutto was a well-known leader in Pakistan and in the international community who demonstrated brave leadership for her people. Israel expresses the hope that Pakistan will continue along the path of reconciliation, moderation and democracy."
Iranian Foreign Ministry spokesman Mohammad Ali Hosseini
"We hope the Pakistani government will identify and bring to justice those behind such a criminal act and restore tranquility to the country."
Speaking to the Islamic Republic News Agency, he said the strike was "aimed to disrupt calm in the neighboring and Muslim country."
Hosseini expressed the sympathy of the Iranian government and nation to the Pakistani government, nation and the relatives of Benazir Bhutto on the tragic event.
Indian Congress Party
"It is a matter for the domestic agencies of Pakistan to investigate. But we must express our deep concern at anything that disrupts and disturbs the even keel of democratic governance in Pakistan," party spokesman Abhishek Singhvi told the Press Trust of India.
Singhvi said Indian democracy loathes the cult of violence, saying "it is not only anti-democratic but also generates instability."
"In her death, an extremely charismatic leader and a naturally engaging speaker has gone."
Russian Foreign Ministry
"We strongly condemn this terrorist act, present our condolences to the family and friends of Benazir Bhutto and hope that Pakistani authorities will provide for national stability," Russian Foreign Ministry spokesman Mikhail Kamynin said Thursday.
The ministry has repeatedly said that the Pakistani government "must do its best to ensure the maximum stability in the election period and prevent terrorist acts against Benazir Bhutto and other political leaders," Kamynin said.
Statement on behalf of French Foreign Minister Bernard Kouchner
Kouchner "expressed vivid emotion following the attack that cost the life of Benazir Bhutto, whom he knew personally. He presents his condolences to her family, to other victims' families in this attack and to the Pakistani people. He strongly condemns this horrible act and he salutes the memory of Mrs. Bhutto, an eminent figure in Pakistan's political life. He reaffirms France's commitment to the stability of Pakistan and its democracy that must be at the center of attention for the international community."
British Foreign Secretary David Miliband
"I am deeply shocked by news of the latest attack in Rawalpindi which has claimed the life of Benazir Bhutto and killed at least 15 other people. My thoughts and sincere condolences go to Mrs. Bhutto's family at this terrible time, as well as to the families of all those who lost their lives in this senseless attack. Benazir Bhutto showed in her words and actions a deep commitment to her country.
"She knew the risks of her return to campaign but was convinced that her country needed her. This is a time for restraint but also unity. All those committed to a stable future for Pakistan will condemn without qualification all violence perpetrated against innocent people.
"In targeting Benazir Bhutto extremist groups have in their sights all those committed to democratic processes in Pakistan. They cannot and must not succeed. The large Pakistani community in the United Kingdom will be gravely concerned about these latest developments. Let me reassure them that the UK government will continue to work with all those who want to build a peaceful and democratic Pakistan."
U.S. Ambassador to the U.N. Zalmay Khalilzad
"Today is not a good day. I knew Benazir Bhutto quite well. She is a friend of mine. and I was very saddened by the news. I send my condolences to her family, her three kids, her husband and of course to the people of Pakistan. It's a great tragedy because she stood for moderation, for rule of law, for democracy in her country, Her death is a loss for the cause of moderation, democracy and rule of law for Pakistan.
"She was clear-headed about the problems of her country, the challenges that she faced, even the security challenges that she faced.
"I call for calm in Pakistan. I call for moderates to come together, to present a united front against extremists and terror, and for success of democracy and moderation in Pakistan. That is important not only for Pakistan but it's also for the future of the world."
Statement issued by the government of South Africa
"South African President Thabo Mbeki, on behalf of the government and people of South Africa and on his own behalf, condemned the assassination of Ms. Benazir Bhutto and other Pakistani nationals in Rawalpindi, Pakistan, earlier today.
"South Africa condemns all forms of violence to promote political objectives and in this regard reiterates its oft-stated view that violence can only beget violence.
"Accordingly, the South African government appeals to all political parties and the people of Pakistan to remain calm during this very turbulent period in its history and remain committed to the political processes towards elections.
"South Africa joins the international community in reaching out in thought and prayer to the family of Benazir Bhutto as well as to those who have lost their loved ones.
"South Africa expresses its confidence that the authorities will leave no stone unturned to ensure that the perpetrators of this heinous act face the full might of the law." E-mail to a friend