Update, 5:49: French officials have confirmed that a French hostage who spoke to journalists has been killed. 

Update, 4:53: The AP has now identified the dead American hostage, by way of unnamed U.S. officials, as Frederick Buttaccio of Katy, Texas, a Houston suburb. It was unclear how he died, though his body has been recovered and his family notified. A LinkedIn profile for a Fred Buttaccio in the Houston area says he was a Sales Operations Coordinator at BP, specializing in accounting. The facility where hostages are still reportedly being held was a gas plant operated for BP and owned by a multinational collective.

Update, 3:52: AP sources — not Algerian state TV — now confirm that one American has died in the hostage standoff.

Update, 2:50: In a briefing, Secretary of State Hillary Clinton called the hostage situation an "act of terror" and said she told her Algerian counterpart that the "utmost care must be taken to preserve innocent life," in an apparent message to the Algerian military.

Update, 2:10 p.m.: Algerian state television now says 12 hostages have been killed in the three-day hostage situation, along with 18 hostage-takers. 

Update, 1:00 p.m. Eastern: The U.S. State Department has confirmed that "Americans are still being held hostage." CBS News reports that three of the five Americans at the BP plant were taken hostage with two having reportedly escaped. The White House said late this morning that it was in "constant contact" with the Algerian government about the situation.

Original post: The Algerian hostage situation is about as serious as its details are hazy, but as it enters its third day reports are emerging that the U.S. Air Force "is in the process of evacuating Americans and other individuals." Algerian state television reported this morning that Thursday's suspect mission by Algeria's military freed 650 hostages — 573 of them Algerian — and that "over half" of the 132 foreign workers held hostage have been freed. That leaves some 60 unaccounted for, with a Mauritanian news site claiming that the militant group behind the attack on a BP gas facility wants to swap two Americans for jailed terror figures. (Update: Algerian state TV is now reporting that 100 of the 132 have been freed.)

The foreign reports, like those on the first and second days of the hostage situation, remain unconfirmed, but the well-placed sources of CNN's Barbara Starr tell her that, a day after the U.S. sent a surveillance drone, help is on the way, with Algerian special forces helping on the ground: 

The U.S. Air Force is in the process of evacuating Americans and other individuals who were involved in the hostage incident at a gas plant in Algeria, a U.S. defense official tells CNN's Barbara Starr. The C-130 is taking the evacuees to Europe, the source said. About 10 to 20 evacuees were expected to be on the flight, according to the source.

And the New York Times's team of Adam Nossiter, Alan Cowell, and Rick Gladstone have a similar account, adding more detail about who might on that plane: 

A United States Africa Command spokesman, Ben Benson, said an Air Force aircraft was in the process of evacuating Americans and people from other countries involved in the hostage event and that they would be flown to an American facility in Europe.

(Update: The White House says it's receiving "regular updates" on the hostage situation. ""We are in constant contact with the Government of Algeria," a spokesman says. "Our first priority is the safety and security of the hostages.)

That may be good news, after Algeria's military got in a stand-off Thursday that reportedly included explosive vests strapped to foreign prisoners, though officials in Britain said that the situation was still ongoing as of early Friday. The Times team writes: 

Speaking in Parliament, Prime Minister David Cameron of Britain said the number of Britons at risk was estimated late Thursday at “less than 30.” That number had now been “quite significantly reduced,” but, he said, he could not give details because Algerian officials had told him the crisis was continuing.

There was apparently still a roadblock near the facility as the militant group demanded negotiations — reportedly for the release of the so-called "Blind Sheikh" — and there may still be those 60 hostages unaccounted for, but stories were beginning to emerge from those hostages that managed to escape. There were early reports that some hostages did escape including two Americans. And In nearly Argo-like fashion, CNN reports that some quick-thinking hostages dressed themselves as a catering staff. CNN reports: 

Some hostages held in Algeria disguised themselves to escape, the head of a catering company which had 150 employees captured, told CNN on Friday.

Regis Arnoux, the chief executive of CIS catering, said the kidnappers separated foreigners from locals and tied the foreigners together at the beginning of the siege, then divided the group when they realized Algerian forces had surrounded the site.

Arnoux isn't exactly as trustworthy or as powerful a source as CNN's U.S. defense officials, but like we said, this situation is unfolding in a haze of detail. We'll update you with more information as it comes in.