It was then that the militants went after the living quarters of the plant instead of disappearing back into the desert.
Information about the 41 foreign hostages the militants claimed to have — which allegedly included seven Americans — was scarce and conflicting. All were reportedly workers at the plant.
The spokesman for the Masked Brigade said 35 of the hostages died in the Algerian strafing. In a phone call with the sound of shelling behind him, he told the Nouakchott Information Agency that the seven surviving hostages on Thursday included three Belgians, two Americans, a Briton and a Japanese citizen.
Algeria's national news service, however, said only four hostages were freed during the military operation Thursday, citing a local law enforcement source.
Earlier in the day before the raid, an Algerian security official had said that 20 foreign hostages had escaped. He was not returning calls after the raid.
The Norwegian energy company Statoil had said 12 of its employees had been captured by the militants — nine Norwegians and three locals — while Japanese media reported at least 3 Japanese among the hostages and Malaysia confirmed two.
Algerian Interior Minister Daho Ould dismissed theories that the militants had come from Libya, 60 miles (100 kilometers) away, or from Mali, more than 600 miles (1,000 kilometers) away. He said the roughly 20 well-armed gunmen were from Algeria itself, operating under orders from Moktar Belmoktar, al-Qaida's strongman in the Sahara.
Yves Bonnet, the former head of France's spy service, also dismissed the idea that the operation was specifically linked to the French action in Mali due to the amount of organization it involved.
"It was an operation conceived well in advance — spectacular and needing a lot of preparation ... It was not at all an improvised operation," he told the Europe 1 radio. "The operation was probably already scheduled and simply getting all those people into the desert would take several days."
It is certainly the largest haul of hostages since 2003, when the radical group that later evolved into al-Qaida in North Africa snatched 32 Western tourists in southern Algeria. This is also the first time Americans have been involved.
BP, the Norwegian company Statoil and the Algerian state oil company Sonatrach, operate the gas field. A Japanese company, JGC Corp, provides services for the facility as well.
Mali and al-Qaida specialist Mathieu Guidere said Algeria's decisive response was in keeping with its usual response to terrorism.
"The message is 'We will terrorize the terrorists,'" he said, adding that the Algerian government had prioritized protecting its gas fields throughout the worst of a violent Islamist insurgency in the 1990s.
Guidere said Algeria's refusal to accept help was also normal.
"They never accept any military help," he said. "They want to do it their way."
Associated Press writers Karim Kabir in Algiers, Kimberly Dozier and Robert Burns in Washington, Lori Hinnant and Elaine Ganley in Paris, and Jill Lawless in London contributed to this report.
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