Al-Qaida confirmed the killing of Osama bin Laden Friday and vowed revenge, saying Americans' "happiness will turn to sadness" in the first statement by the terror network since its leader was slain in a U.S. commando raid against his Pakistani hideout.

On Friday, May 6, hundreds of members of radical Islamic parties protested in several Pakistan cities against the American raid and in favor of bin Laden. Many of the people chanted "Osama is alive" and blasted the U.S. for violating the country's sovereignty.

The largest rally took place in the town of Khuchlak in southwestern Baluchistan province, where about 500 people attended, AP reported.

"America is celebrating Osama bin Laden's killing, but it will be a temporary celebration," said Abdullah Sittar Chishti, a member of the Jamiat Ulema Islam party who attended the rally in Khuchlak. "After the martyrdom of Osama, billions, trillions of Osamas will be born."