GAZA, (Reuters) – Palestinian gunmen surrounded European Union offices in the Gaza Strip on Thursday, threatening violence and demanding an apology for caricatures of the Prophet Mohammad that appeared in European newspapers.

About a dozen gunmen, from the militant group Islamic Jihad and an armed faction of Fatah known as the Yasser Arafat Brigades, climbed the surrounding walls of the compound and fired into the air before leaving the scene, witnesses said.

The gunmen demanded an apology for the Danish cartoons, one of which shows the Prophet Mohammad wearing a turban shaped like a bomb. They set a 48-hour deadline.

“We will watch the office closely and if European countries continued their assaults against Islam and against the Prophet Mohammad, we will turn this office into ruins,” a spokesman for the Yasser Arafat Brigades told Reuters.

Another armed Fatah group, called the Abu el-Reesh Brigades, said citizens of Norway, Denmark, France and Germany in Gaza “will be in danger” if their governments do not apologise within 10 hours.

Ahmed Qurie, who remains as Palestinian prime minister until the formation of a new government following Hamas’s landslide election victory last week, warned armed groups against threatening the Europeans.

“We cannot accept any group that takes the law into its own hands,” Qurie said.

An EU official said, “Threats to our staff are unacceptable.”

The official, speaking on condition of anonymity, said Palestinian police have been deployed outside the building, adding: “Everything is back to normal.”

He said EU staff left the building just before the protest started and have now returned to work.

Several European journalists left Gaza for their own safety.

A diplomatic storm has erupted over the cartoons, which were published in a Danish newspaper in September and republished in Norway last month. Newspapers in France, Germany and Spain have also reprinted the caricatures.

Islamic tradition prohibits realistic depictions of prophets, and considers caricatures of them blasphemous.

Earlier this week, Syria recalled its ambassador from Denmark in protest, and the Danish embassy in Damascus was evacuated after a bomb threat that turned out to be a hoax.

Two large Danish companies have reported their sales falling in the Middle East after protests against the cartoons in the Arab world and calls for boycotts.