A mob attacked a United Nations compound in the northern Afghani city of Mazar-i-Sharif Friday, beheading two employees and killing at least six others. It came in response to an American pastor's decision to make good on his promise to burn a Quran last month. The rioting erupted after mosque preachers sermonized the burning, sending upwards of 1,000 worshippers into the streets in a rage.

Pastor Terry Jones created an international incident last year when he threatened to burn a Quran on the anniversary of the 9/11 attacks. The initial threat sparked a worldwide debate about respect for Islam on one hand and free speech on the other. While he backed down on his initial threats, last month the controversial pastor put the Quran on trial and burned the kerosene-soaked book after finding it guilty. While many knew of his initial threat and recanting, Jones' Quran trial and burning were less known.

The news reached Afghanistan and sparked the same outrage of Jones' initial threats. As many as 1,000 protesters burned American flags and chanted "Death to America, Death to Israel." They later attacked a U.N. compound in the city, murdering five Filipino guards and 3 other foreigners at the facility. More than 100 protesters were injured and at least four were killed after Afghani police intervened.

U.N. Secretary General Ban Ki-moon described the attack as "outrageous and cowardly," even as U.N. spokesman Dan McNorton said the organization was trying to "ascertain all the facts and take care of all our staff."

President Obama condemned the killings "in the strongest possible terms" and saluted U.N. work as "essential to building a stronger Afghanistan."