There can be no excuses for murdering innocent people simply because a book was burned half-way around the world.

KABUL, Afghanistan — Fearing for their lives, the U.N. workers dashed into a dark bunker hoping to escape the mob of Afghan protesters angry over the burning of a Quran by a Florida church.

Hope wasn’t enough for three of them. They were hunted down and brutally slain — their bodies found later in three different parts of the compound in northern Afghanistan.

“They were killed when they were running out of the bunker,” said Staffan de Mistura, the top U.N. envoy in Afghanistan, who recounted their harrowing deaths to reporters on Saturday evening. “One was pulled out alive because he pretended to be a Muslim.”

De Mistura spoke in a somber tone as he described how three U.N. staff members and four Nepalese guards were killed Friday when the protesters stormed their compound in the normally peaceful city of Mazar-i-Sharif. He placed direct blame on those who burned a copy of the Muslim holy book in Gainesville, Florida, last month, stoking anti-foreign sentiment that already was on the rise after nearly a decade of war in Afghanistan.

“The demonstration was meant to protest against the insane and totally despicable gesture by one person who burned the holy Quran,” he said.

He also said the U.N. building would not have been attacked if there had been an adequate cordon of Afghan police separating the demonstrators and the compound.

Four of the Nepalese guards were killed; some were shot in the yard of the compound. Three Afghan U.N. workers survived by melding into the surging crowd, he said. Four Afghan protesters also were killed in the riot.

Protesters had set fire to cars and an electric generator in the U.N. compound so the bunker was dark. It was the only safe place for the four foreign U.N. workers on the compound, including the Russian chief of mission. But the door of the bunker was made to withstand a bomb attack, not the sheer force of a crowd of people trying to get inside.

When the killers forced themselves inside they saw Pavel Ershov, the mission chief who is fluent in Dari, one of two languages spoken in Afghanistan. They beat him, but stopped after he convinced them, in Dari, that he was a Muslim, de Mistura said.

“He spoke the language and tried to draw their attention on himself,” the envoy said. “For a moment, he hoped that they would think there was nobody else there.”

But using a light, the attackers found the three other foreigners, then pulled them out and killed them one after the other. Two died of bullet wounds. The third was killed with a knife to the throat.