ALGIERS, Algeria (AP) -- An Algerian military raid to free hostages from at least 10 countries at a remote Sahara natural gas complex and wipe out their Islamist militant captors unleashed bloody chaos, and the British government said Friday that the situation was not yet over.
The fate of the fighters and many of the captives remained uncertain, and dueling claims from the military and the militants have muddied the world's understanding of an event that angered Western leaders.
By nightfall, Algeria's government said the raid was over. But Britain's Foreign Office said Friday morning that "the terrorist incident remains ongoing." It said it could give no further details. Manuel Valls, France's interior minister, said the situation remained murky.
At least six people, and perhaps many more, were killed -- among them Britons, Filipinos and Algerians. Terrorized hostages from Ireland and Norway trickled out of the Ain Amenas plant. Dozens more remained unaccounted for: Americans, Britons, French, Norwegians, Romanians, Malaysians, Japanese, Algerians and the fighters themselves.
"This remains a fluid and evolving situation and many details are still unclear, but the responsibility for the tragic events of the last two days squarely rests with terrorists who chose to attack innocent workers, murdering some and holding others hostage," British Foreign Secretary William Hague told Sky News from Australia.
Algeria's army-dominated government, hardened by decades of fighting Islamist militants, shrugged aside foreign offers of help and drove ahead alone, keeping a tight control of information even to Western leaders.
On Friday, Algeria's ambassador to Japan was summoned by the senior vice minister of foreign affairs, who demanded that Algeria prioritize hostages' lives and cooperate closely.
Prime Minister David Cameron spoke twice to his Algerian counterpart on Thursday and was "prepared for bad news," Britain's Foreign Office said.
A U.S. official said late Thursday that while some Americans escaped, other Americans remain either held or unaccounted for. The official spoke on condition of anonymity because he wasn't authorized to discuss the matter publicly.
The U.S. government sent an unmanned surveillance drone to the BP-operated site, near the border with Libya and 800 miles (1,290 kilometers) from the Algerian capital, but it could do little more than watch Thursday's intervention.
With the hostage drama entering its second day Thursday, Algerian security forces moved in, first with helicopter fire and then special forces, according to diplomats, a website close to the militants, and an Algerian security official. The government said it was forced to intervene because the militants were being stubborn and wanted to flee with the hostages.
The militants -- led by a Mali-based al-Qaida offshoot known as the Masked Brigade -- suffered losses in Thursday's military assault, but garnered a global audience.
Even violence-scarred Algerians were stunned by the brazen hostage-taking Wednesday, the biggest in northern Africa in years and the first to include Americans as targets. Mass fighting in the 1990s had largely spared the lucrative oil and gas industry that gives Algeria its economic independence and regional weight.
Casualty figures in the Algerian standoff varied widely. The remote location is extremely hard to reach and was surrounded by Algerian security forces -- who, like the militants, are inclined to advertise their successes and minimize their failures.
"An important number of hostages were freed and an important number of terrorists were eliminated, and we regret the few dead and wounded," Algeria's communications minister, Mohand Said Oubelaid, told national media, adding that the "terrorists are multinational," coming from several different countries with the goal of "destabilizing Algeria, embroiling it in the Mali conflict and damaging its natural gas infrastructure."
The official news agency said four hostages were killed in Thursday's operation, two Britons and two Filipinos. Two others, a Briton and an Algerian, died Wednesday in an ambush on a bus ferrying foreign workers to an airport. Citing hospital officials, the APS news agency said six Algerians and seven foreigners were injured.
APS said some 600 local workers were safely freed in the raid -- but many of those were reportedly released the day before by the militants themselves.
The militants, via a Mauritanian news website, claimed that 35 hostages and 15 militants died in the helicopter strafing. A spokesman for the Masked Brigade told the Nouakchott Information Agency in Mauritania that only seven hostages survived.
President Barack Obama and Cameron spoke on the phone to share their confusion. White House Press Secretary Jay Carney said the Obama administration was "seeking clarity from the government of Algeria."
Militants earlier said they were holding seven Americans, but the administration confirmed only that Americans were among those taken. The U.S. government was in contact with American businesses across North Africa and the Middle East to help them guard against the possibility of copycat attacks.
BP, the Norwegian company Statoil and the Algerian state oil company Sonatrach, operate the gas field and a Japanese company, JGC Corp, provides services for the facility.
One Irish hostage managed to escape: electrician Stephen McFaul, who'd worked in North Africa's oil and natural gas fields off and on for 15 years. His family said the militants let hostages call their families to press the kidnappers' demands.
"He phoned me at 9 o'clock to say al-Qaida were holding him, kidnapped, and to contact the Irish government, for they wanted publicity. Nightmare, so it was. Never want to do it again. He'll not be back! He'll take a job here in Belfast like the rest of us," said his mother, Marie.
Dylan, McFaul's 13-year-old son, started crying as he talked to Ulster Television. "I feel over the moon, just really excited. I just can't wait for him to get home," he said.
At least one Filipino managed to escape and was slightly injured, the Philippine Foreign Affairs Department said. Spokesman Raul Hernandez said he had no information about any fatalities.
Algerian Interior Minister Daho Ould Kabila said the 20-odd militants entered the country from nearby Libya in three vehicles, in an operation commanded by extremist mastermind Moktar Belmoktar, who is normally based in Mali.
The militants made it clear that their attack was fallout from the intervention in Mali. One commander, Oumar Ould Hamaha, said they were now "globalizing the conflict" in revenge for the military assault on Malian soil.
France has encountered fierce resistance from the extremist groups in Mali and failed to persuade many allies to join in the actual combat. The Algeria raid could push other partners to act more decisively in Mali -- but could also scare away those who are wary of inviting terrorist attacks back home.
Associated Press writers Karim Kabir in Algiers, Bradley Klapper, Kimberly Dozier and Robert Burns in Washington, Lori Hinnant and Elaine Ganley in Paris, Shawn Pogatchnik in Dublin, Bjoern H. Amland in Oslo, Norway, Mari Yamaguchi in Tokyo and Cassie Vinograd and Jill Lawless in London contributed to this report.