STORY HIGHLIGHTS
- NEW: U.S. rejects reported prisoner exchange offer from jihadist spokesman
- It's unclear how many hostages are left at the remote gas facility
- An escaped hostage says explosives were tied to his neck
- Attackers apparently are upset that Algeria supported anti-terror operations in neighboring Mali
(CNN) -- Militants strapping plastic explosives around the necks of foreign workers seized in the remote Algerian desert. Hostages secretly inventing disguises to escape their captors.
These are just some of the few concrete details that have emerged from the survivors of a massive terrorist assault on an Algerian gas field, an ordeal that is entering a third day.
It isn't clear how many hostages were initially seized by the Islamic militants, how many are still being held or how many have been killed. Some may still be hiding in the complex, according to the state-run Algerian Press Service.
The press service said Friday that an Algerian military operation freed 650 hostages, including 100 foreigners. At least 30 foreign workers are still unaccounted for, according to the unconfirmed media report.
It said there were numerous casualties in the military operation, without offering details.
Facing criticism that it didn't alert other countries before launching its military operation Thursday, Algeria said it had to act fast before the hostages were moved to another country.
Like most of the information about the situation, there are conflicting reports over whether the operation is still ongoing.
Algeria's state media reported it was over, but British Prime Minister David Cameron said Friday morning that the Algerians were still pursuing terrorists and possibly hostages at the large and complex site.
It all started Wednesday, when the al Qaeda-linked militants -- apparently angry about Algeria's support in a rout of their comrades in neighboring Mali -- targeted the remote gas field, which is operated by Algeria's state oil company in partnership with foreign companies, including Britain's BP and Norway's Statoil.
The massive gas field is in the southern Algerian town of In Amenas, just 60 kilometers (37 miles) from the Libyan border.
Officials from Britain, the United States, Norway, France, Malaysia and Japan have said their nationals are also among those involved, without offering further details, citing conflicting reports.
Cameron said Friday that the number of Britons unaccounted for is "significantly" fewer than 30.
A reported offer to negotiate the release of an unknown number of American hostages has been rejected by the United States.
A spokesman for Moktar Belmoktar, a veteran jihadist who leads the the Brigade of the Masked Ones, which has claimed responsibility for the kidnappings, made the offer in an interview with a Mauritanian private news agency.
The spokesman said Belmoktar is willing to release the American hostages in exchange for Sheikh Omar Abdel Rahman, the mastermind behind the 1993 World Trade Center bombing, and Aafia Siddiqui, a Pakistani woman who is jailed in the United States on terrorism charges.
When asked Friday about the reported prisoner exchange offer, State Department spokeswoman Victoria Nuland restated the United States' policy of not negotiating with terrorists.
It's unclear how many Americans are being held. There could be as few as three American hostages, two U.S. officials said Wednesday.
A dangerous escape
At the beginning of the siege, the militants rounded up all the Westerners into one group and tied them up, according to survivors' accounts.
The kidnappers were equipped with AK-47 rifles and put explosives-laden vests on some of the hostages, a U.S. State Department official said.
Some were able to escape by disguising themselves, according to Regis Arnoux, who runs a catering firm at the site and spoke to some of his 150 employees who were freed. He said they all were "traumatized" by their ordeal as hostages.
Some Algerian hostages were free to walk around the site but not to leave, according to Arnoux. Some managed to escape by themselves.
As the Algerian military launched its operation, the militants moved some of the hostages, according to one survivor's account.
With plastic explosives strapped around their necks, these hostages were blindfolded and gagged before being loaded into five Jeeps, according to the brother of former hostage and British national Stephen McFaul.
McFaul managed to escape after the vehicle he was in -- one of several targeted by Algerian fighters -- crashed, with the explosives still around his neck, his brother told CNN's Matthew Chance.
"The joy was unreal," Brian McFaul said upon hearing that his brother was safe. "I haven't seen my mother move as fast in all my life, and my mother smile as much, hugging each other. ... You couldn't describe the feeling."
Sadly, McFaul said the other four Jeeps were "wiped out" in an explosion, and his brother believed that the hostages inside did not survive.
Nations react
Britain has deployed a team of trauma experts and consular affairs officers who can issue emergency passports to a location about 450 kilometers (280 miles) away from the besieged plant, a Foreign Office official said.
"It's the kind of thing we have done before in similar situations," the official said. "This is us getting as close and as ready as we can."
Those freed include some Americans, while other U.S. nationals are still unaccounted for, U.S. officials said.
"This incident will be resolved -- we hope -- with a minimum loss of life," U.S. Secretary of State Hillary Clinton said Thursday. "But when you deal with these relentless terrorists, life is not in any way precious to them."
U.S. Defense Secretary Leon Panetta, speaking in London, said the United States was working round the clock to ensure the safe return of its citizens.
The U.S. is evacuating between 10 and 20 people caught up in the hostage-taking, a U.S. defense official told CNN on Friday.
They will be taken to U.S. facilities in Europe, the official said, and the condition of those who are injured will be assessed.
BP said Friday that a "small number of BP employees" are still unaccounted for, while Norway's Statoil said the fate of eight of its employees at In Amenas was still uncertain. Nine other Statoil workers who were at the plant are safe, it said.
Both firms are pulling personnel from Algeria, which is Africa's largest natural gas producer and a major supplier of natural gas to Europe.
BP said it had flown 11 of its own employees and several hundred staff from other companies out of the North African country Thursday and expected another flight Friday.
Three workers for a Japanese engineering company that was working on the site have been contacted and are safe, said Takeshi Endo, a senior manager for JGC Corp. But the company had not been able to contact 14 others, he said.
CNN affiliate BFM-TV reported that a French nurse who was working at the site at the time of the attack had been freed.
'Terribly disappointed'
Algeria faces tough questions from the governments of kidnapped nationals over its handling of the crisis amid fears that hostage safety is not being put first.
Neither the United States nor Britain was informed before Algeria's military operation Thursday.
But, speaking to lawmakers Friday, Cameron stressed that militants were to blame for the attack.
At least one Briton has been killed in the incident.
Japanese Vice Minister Shunichi Suzuki summoned the Algerian ambassador Friday to express Tokyo's concern, the Japanese Foreign Ministry said. And Japanese Prime Minister Shinzo Abe is cutting short a foreign trip to deal with the crisis, his office said.
"There is so much conflicting information on safety of the hostages," Chief Cabinet Secretary Yoshihide Suga told reporters in Tokyo. "Safety of 14 Japanese citizens still remains unknown."
He said Japanese officials had urged the Algerian government to avoid exposing the hostages to danger. "We are terribly disappointed about the Algerians' military operation," he said.
Before the Algerians launched the operation, U.S. officials urged them to be cautious and make the hostages' safety their first priority, an Obama administration official said.
A senior U.S. official said U.S. officials did not trust the information they were getting from the Algerians, "because we hear one thing and then we hear something else."
Algerian forces went in Thursday after noticing the hostages being moved toward "a neighboring country," where kidnappers could use them "as a means of blackmail with criminal intent," Algerian Communications Minister Mohamed Said told state television.
Algerian troops fired on at least two SUVs trying to leave the facility, Algerian radio said. And a reporter saw clashes near the site, the Algerian Press Service and radio reports said.
"There were a number of dead and injured, we don't have a final figure," the communications minister said.
The man behind the group claiming responsibility for the attack and kidnappings is a veteran jihadist known for seizing hostages.
Belmoktar, the veteran jihadist, is an Algerian who lost an eye fighting in Afghanistan in his teens. He has long been a target of French counterterrorism forces. Libyan sources said he spent several months in Libya in 2011, exploring cooperation with local jihadist groups and securing weapons.
The militants said they carried out the operation because Algeria allowed French forces to use its airspace in attacking Islamist militants in Mali. Media in the region reported that the attackers issued a statement demanding an end to "brutal aggression on our people in Mali" and cited "blatant intervention of the French crusader forces in Mali."
French Prime Minister Jean-Marc Ayrault said the Algerian hostage situation "confirms the gravity of the terrorist threat and the necessity to fight it with a determined and united front."
CNN's Barbara Starr, Dan Rivers, Mitra Mobasherat, Saskya Vandoorne, Laura Perez Maestro, Junko Ogura, Dheepthi Namasivayam, Saad Abedine, Elise Labott, David Mattingly, Athena Jones, Jethro Mullen, Tim Lister, Joe Sterling and Greg Botelho contributed to this report, as did journalists Peter Taggart from Belfast and Said Ben Ali from Algiers.
