PAKISTAN (ANS) -- Former Pakistani Prime Minister Benazir Bhutto was assassinated in an election-rally attack in Rawalpindi, threatening the stability of a nuclear-armed nation that is a focal point of the West`s war on terror. Bloomberg News reported that police said at least 16 people died and more than 60 were injured in the gunfire-and-bomb attack on Bhutto`s rally. The opposition leader, 54, had survived a previous attempt on her life when she returned from exile two months ago. Bloomberg said that rioting broke out as her supporters gathered outside the hospital where her death was confirmed and in cities across Pakistan. President Pervez Musharraf, who had allowed her return to participate in parliamentary elections planned for Jan. 8, appealed for calm in a message broadcast on state television. "I don`t think elections will be possible now,"` Hassan Abbas, a Pakistani political analyst at Harvard University, told Bloomberg. The Pakistan Christian Post reported that Christians in Pakistan condemned the killing, and said that Nazir S. Bhatti, President of Pakistan Christian Congress, has declared Dec. 27 2007, as a "Black Day" in the history of Pakistan. He called Bhutto the voice of democracy and the poor. The Post said Bhatti called the "death of (BB) a grave challenge to the government on the safety and security of the people of Pakistan, and a total failure of the establishment. It was the responsibility of the government to secure the life of Benazir Bhutto, but it seems that security measures were neglected and (this) sad incident happened." Bhatti said, "Pakistani Christians extend (their) grief on the death of Benazir Bhutto, and demand (justice) and the immediate arrest of the culprits." Bloomberg said that the death of the nation`s most popular politician also deepens a vacuum within its civilian leadership to the benefit of the two other communities that strive to rule Pakistan: the military and Islamic militant movements. "`Long-term, it raises very, very serious questions about the stability of Pakistan,"` Farzana Shaikh, Pakistan analyst at the London-based Chatham House foreign policy institute, told Bloomberg in a phone interview from Montpellier, France.