Hundreds of thousands of Palestinians flooded Gaza's streets Monday to bury Hamas founder Sheik Ahmed Yassin, who was assassinated by an Israeli missile earlier in the day.

U-N Secretary-General Kofi Annan joined world leaders in condemning Monday's killing of Yassin, the highest-profile Palestinian militant targeted by Israel during the most recent intifada.

After an initial silence, the Bush administration denounced Israel for the killing, saying it was "deeply troubled" by the attack and that it had no advance warning of the assassination plan.