-- Twelve hostages have been killed since the Algerian military launched a ground operation on Thursday, the official Algerian news agency said, quoting a security source.
-- State-run Algerian Radio cited an official source as saying that the major military raid that was launched Thursday was over, but that there was "ongoing activity at various locations" near the plant.
Number of hostages
-- Hundreds of people, including hundreds of Algerian workers and 132 foreign workers, were taken hostage Wednesday, according to the state-run Algerian Press Service. CNN has not independently confirmed the numbers.
-- By Friday, 650 hostages have been freed by the Algerian military, according to the state-run Algerian Press Service. Of the 132 foreign workers taken, 100 were released, the agency said. CNN has not independently confirmed the report.
-- The Al-Mulathameen Brigade initially said that 41 "Westerners, including seven Americans, (as well as) French, British and Japanese citizens have been taken hostage," the Mauritanian News Agency and Sahara Media report.
Islamist militants claim responsibility
-- The Al-Mulathameen Brigade, which is associated with al Qaeda in the Islamic Maghreb, claims responsibility for the attack, according to media in the region.
-- A spokesman for Al-Mulathameen told media in the region that the militants claimed to have carried out the operation because Algeria allowed French forces to use its airspace in attacking Islamist militants in Mali. (However, a U.S. official told CNN that the operation's sophistication suggests that it likely was planned well in advance of France's Mali action.)
-- How many people were taken hostage?
-- How many people have been killed?
-- Is the attack directly related to the fighting in Mali, as the militants claim?