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As many as 34 hostages and 15 hostage-takers were reportedly killed in Algeria after Algerian forces launched an air strike on a BP facility that has been held by radical Islamists since Wednesday.
The figures come from a Mauritanian news agency that has been "in constant contact" with the kidnappers, Reuters said, but added that it was not possible to verify the report at this time.
Algerian troops had the complex surrounded and began firing on it from helicopters, according to a report from Mauritania's ANI news agency cited by Reuters.
Earlier, around 25 foreign hostages reportedly escaped from the In Amenas gas field in southeast Algeria, where the gunmen have been holding dozens of people captive.
A separate report of a successful escape is also unverified. Algerian television said that 40 Algerian hostages had been freed and 15 foreigners had escaped, according to Reuters, though an Algerian security source told the news agency that 25 people had fled.
Another Algerian official told the Associated Press that there were 20 foreign escapees, Americans and Europeans among them.
The captors demanded safe passage out of Algeria and into Libya, wrote CNN, while Algeria stated that it will not negotiate with terrorists.
More from GlobalPost: Militants kidnap foreigners from Algerian BP plant
Another report said a group calling itself the "Battalion of Blood" claimed to have kidnapped 41 foreigners, including US, Japanese, British, French and Norwegian citizens. They were also reportedly holding an unknown number of Algerians at the gas plant, which is run jointly by British, Algerian and Norwegian firms.
Algerian Interior Minister Daho Ould Kablia said that the kidnappers were led by Mokhtar Belmokhtar, a former commander with Al Qaeda in the Islamic Maghreb, who left the armed group to set up his own faction late last year, the BBC reported.
The captors reportedly demanded an end to France's campaign against Islamist insurgents in Mali, as well as the release of 100 Islamist prisoners.
The governments whose nationals are among the hostages have been holding emergency meetings throughout the night. According to the AP's information, Algeria was in talks with the US and France about the possibility of sending in an international force to rescue the captives.