(NBC NEWS) -- Western hostages being held by Islamist militants at a gas plant in Algeria were feared to have been killed during a raid by Algerian forces Thursday. At least some hostages, however, reportedly escaped.
The gas plant near In Amenas, Algeria.
State media reported Thursday evening that the military operation had ended at the remote desert facility where dozens of workers — including three Americans — had been held hostage. The Algerian government was reported as saying two Filipinos and two British hostages had been killed.
Some of the hostages reportedly escaped from the natural gas pumping plant, near In Amenas, close to the Libya border. An unknown number of hostages left the country on a charter flight and were expected to land at London's Gatwick airport near midnight Thursday, BP, which operates the complex, told NBC News. The company would not confirm the nationalities of the hostages on the flight.
Unconfirmed reports from local sources cited by Reuters and The Associated Press said hostages and militants had been killed in the operation, but reporting on the number of casualties differed wildly — from four hostages killed to 35.
U.S. officials called the hostage situation "murky" and said the U.S. is working with the Algerian government and other affected nations to try to resolve the situation as quickly and securely as possible.
"It's in a remote area of Algeria, near the Libyan border," Secretary of State Hillary Clinton said. "The security of our Americans who are held hostage is our highest priority, but of course we care deeply about the other Algerian and foreign hostages as well."
Clinton said she could not provide any additional information about the situation.
An Ireland government spokesman said Thursday that an Irish national held at the In Amenas gas plant had "made contact with his family and is understood to be safe and well, and no longer a hostage."
Sky News in London identified the Irish survivor as Stephen McFaul, 46, from west Belfast.
In an interview with the television station, McFaul's father Christopher said he was "delighted" by the news but added he felt "sorry for the other hostages that are still there."
He also described the last 48 hours as "hell".
Stephen McFaul's son, Dylan, also spoke to the Sky reporters: "I can't even explain the excitement. I can't wait until he gets home again," he said, adding that he would tell his father "he's never going back there and I'm not letting him".
Islamists stormed the plant and workers' housing before dawn Wednesday and claimed to have seized 41 foreign workers - from countries that included the United States, France, Ireland, Britain, Japan and Norway — and local employees.
The Associated Press, citing claims from militants, said Algerian military helicopters attacked the kidnappers Thursday morning.
According to the AP, militants with the Masked Brigade, a Mali-based al-Qaida offshoot, provided updates through a Mauritanian news organization that said the Algerians attacked when the militants tried to move hostages from the energy complex. The group claimed that 35 hostages and 15 militants died but seven hostages survived the helicopter attack on its convoy.
A local resident near the plant told Reuters the Algerian military had opened fire and that "many people" were killed.
Twenty hostages of an Algerian militant group with ties to al Qaeda in a standoff with the Algerian Army are reported to have escaped Thursday. Over 41 hostages of several nationalities, including Americans, were being held in a BP gas facility. NBC's Michelle Kosinski reports.
Faycal Metaqui, a journalist at Algerian newspaper El Watan, told French news channel BFM that he was unable to confirm with authorities the earlier reports that some hostages had escaped.
"Sadly, there have been some reports of casualties, but we are still lacking any confirmed or reliable information," said a statement from oil giant BP, which is a joint owner of the plant.
The crisis — one of the biggest international hostage incidents in decades — opened an international front in the civil war in neighboring Mali after French troops launched an offensive against Islamist rebels linked to al-Qaida in that country.
The group that has claimed responsibility for the Islamists' raid is said to be led by a jihadist called Mokhtar bel Mokhtar, whose nicknames include "The Uncatchable" and "Mr. Marlboro."
The militants have demanded an end to the French military campaign in Mali, where hundreds of French paratroopers and marines are launching a ground offensive against rebels a week after Paris began firing on militants from the air.