A mob inflamed by a mosque sermon describing the burning of the Muslim holy book by an American pastor attacked a U.N. compound in a northern Afghan city on Friday, killing at least eight foreign staffers, according to Afghan police.

A spokesman for the U.N. mission in Afghanistan, Dan McNorton, confirmed that there had been deaths of U.N. personnel in the city of Mazar-e-Sharif, but said he did not have further details.

Sherjan Durrani, a spokesman for the provincial police, identified the dead as guards at the U.N. compound who were believed to be from the Philippines. However, some Afghan news reports said the dead included guards who were overpowered in the attack as well as other U.N. workers who were inside the compound at the time.

Durrani said four rioters had also been killed and that more than 100 others were injured in the outbreak of violence in the northern city, normally one of the calmer corners ofAfghanistan.

The rioting erupted after mosque preachers at Friday prayers — the most important of the Muslim week — sermonized against the burning of the Quran by an American evangelical pastor in Florida.

The March 20 burning, at the Dove World Outreach Center, drew little attention in the United States, even though the church’s pastor, Terry Jones, drew international attention last year when he threatened to torch a Quran on Sept. 11.

But reports of the March incident, in which church members held a mock trial of the Quran and condemned it as inciting murder before soaking a copy in kerosene and burning it, were circulated on the Internet, igniting anger half a world away.

After the Friday service in Afghanistan, up to 1,000 worshipers marched on the U.N. compound and overran it, police said.

Durrani said order was restored and that about two dozen people had been arrested for taking part in the attack.

The attack was quickly condemned by President Barack Obama: “”I condemn in the strongest possible terms the attack on the United Nations Assistance Mission in Afghanistantoday.

“”The brave men and women of the United Nations, including the Afghan staff, undertake their work in support of the Afghan people. Their work is essential to building a strongerAfghanistan for the benefit of all its citizens. We stress the importance of calm and urge all parties to reject violence and resolve differences through dialogue.””

McNorton, the U.N. spokesman, said the head of the world body’s mission in Afghanistan, Staffan de Mistura, was traveling to Mazar-e-Sharif, which is north of the capital, Kabul. Even hours after the attack, he said neither the death toll nor the nationalities of those killed could be confirmed.

“”The situation is still confusing, and we are currently working to ascertain all the facts and take care of all our staff,”” he said.

Friday’s violence was the worst attack against U.N. staffers in Afghanistan since October 2009, when gunmen and bombers stormed a guesthouse in the capital, killing five foreign U.N. workers and two guards. That prompted the world body to order the relocation of hundreds of expatriate employees.

Hundreds of people also took part in an anti-Quran-burning protest Friday in Kabul, massing near a heavily guarded area where the U.S. Embassy and the headquarters of the NATO force is located. But the demonstrators eventually dispersed without incident.