Baghdad, Iraq ? Iraqi militants executed one of four Italian hostages, officials in Rome confirmed Wednesday — the first known execution of any of the 22 foreigners being held in Iraq.

The killing could further heighten fears among international aid workers, contractors and journalists, some of whom are already restricting their activities in the country.

Earlier Wednesday, a French journalist was freed after a four-day hostage ordeal and Russia announced it would evacuate its citizens.

The militants who killed the Italian hostage demanded the withdrawal of U.S. forces from Iraq and threatened to kill the three other hostages, Al-Jazeera reported.

The Arab TV network reported it had video of the killing but did not broadcast it because it is too graphic. Al-Jazeera did show footage of the four Italian security guards sitting on the ground, holding up their passports and surrounded by armed men.

The Italian ambassador to Qatar, where the network is based, watched the video and confirmed the man killed was Fabrizio Quattrocchi, one of the kidnapped Italians, Italian Foreign Minister Franco Frattini said.

Frattini said the government would do “what is possible and impossible” to free the remaining three.

Italy is the third-largest coalition partner in the occupation force. Italy didn’t send in combat troops during the war. Its forces are based in the southern city of Nasiriyah, working on reconstruction.

In November of last year, Italy suffered losses when a suicide truck bomb attack in Nasiriyah killed 19 Italians — Italy’s worst single military loss since World War II.

Meanwhile, U.S. officials and the top U.S contractor in Iraq, Halliburton, were trying to determine whether four bodies found belonged to seven Americans missing since gunmen attacked their convoy outside Baghdad on Friday.

One of the missing — Thomas Hamill, a 43-year-old truck driver — is known to have been abducted. His captors have threatened to kill and mutilate him unless U.S. troops ended their assault on Fallujah. The deadline passed Sunday with no word on his fate.

State Department spokesman Richard Boucher declined comment on reports that the bodies were mutilated.

A U.S. spokesman said Tuesday that 40 foreigners from 12 countries are being held by kidnappers — but an Associated Press count put the number at 22, with Wednesday’s release of the French journalist.