JAKARTA, Indonesia — Hundreds of Muslims protesting caricatures of the Prophet Muhammad tried to storm the U.S. Embassy today, smashing the windows of a guard post but failing to push through the gates. Several people were injured. Pakistani security forces, meanwhile, sealed off the capital of Islamabad to block a planned mass demonstration and fired tear gas and gunshots to chase off protesters. In Turkey, tens of thousands gathered in Istanbul chanting slogans against Denmark, Israel and the United States.