El Mokhtar Ould Sidi, editor of the Mauritanian news site ANI, said several calls on Thursday came from the kidnappers themselves giving their demands and describing the situation.
"They were clearly in a situation of war, the spokesman who contacted us was giving orders to his colleagues and you could hear the sounds of war in the background.... He threatened to kill all the hostages if the Algerian forces tried to liberate them," he said.
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.
Militants claimed 35 hostages died when the military helicopters opened fire as they were transporting hostages from the living quarters to the main factory area where other workers were being held.
The group — 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.
The militants made it clear that their attack was in revenge for the French intervention against Islamists who have taken over large parts of neighboring Mali. France has encountered fierce resistance from the extremist groups in Mali and failed to persuade many Western allies to join in the actual combat.
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.
The official Algerian 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 the initial militant ambush on a bus ferrying foreign workers to an airport. Citing hospital officials, it 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.
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.
Schemm reported from Rabat, Morocco. Associated Press writers Bradley Klapper, Lolita Baldor and Robert Burns in Washington, Lori Hinnant in Paris, Shawn Pogatchnik in Dublin, Bjoern H. Amland in Oslo, Norway, Mari Yamaguchi in Tokyo and Cassandra Vinograd, Paisley Dodds and Jill Lawless in London contributed to this report.