First came the crackle of automatic gunfire, then a siren blasted out over the desert air alerting the hundreds of workers at the sprawling natural gas complex in eastern Algeria that something was badly wrong.

In the chaos, AK-47-wielding militants – some bearded; others clean-shaven – began to round up workers, menacing them with their weapons, screaming instructions and threatening instant death in the face of disobedience. Just before storming the complex the militants ambushed nearby a bus carrying employees and killed a Briton and an Algerian.

Not all of the hundreds of workers at the In Amenas natural gas facility near the Libyan border were taken captive. The quick-witted or those lucky enough to be secreted in far-flung buildings had time to elude their two-dozen or so would-be captors, militant Islamists loyal to the one-eyed Jihadist leader Mokhtar Belmokhtar.

Heavily out-numbered by the facility’s workers, the militants didn’t attempt to corral everyone: they were on the look out for prized foreigners – Westerners who if captured, could be worth big ransom money and whose captivity would assure worldwide publicity.

An engineer told the French radio station, France Info that the attackers searched the base, shouting, “We’re only looking for foreigners, you Algerians can go!” According to the engineer, who declined to give his name, the militants “seemed to be Libyan and Algerian…were extremely well armed, and at ease. Aged between 30 and 35 years. Carrying bombs.”

As Algerian security forces launched a second assault today to try to free hostages still being held in the complex jointly run by BP, the Norwegian company Statoil, and Algeria’s state oil agency, harrowing accounts of the three-day hostage crisis began to emerge from the 600 captives who’d escaped or were liberated in the first savage rescue mission launched by the Algerians.

That rescue mission on Thursday has provoked the fury of foreign leaders, who as the hostage crisis stretched into a third day have accused the Algerians of failing to try to negotiate an end to the worst hostage crisis in North African history and of mounting an unskillful operation that was bound to lead to a bloody outcome.

British Prime Minister David Cameron expressed his frustration in the House of Commons, lambasting Algeria for refusing repeated offers of assistance ahead of the assault and blasting the Algerian government for failing to consult about the “all guns blazing” rescue mission despite his demand to be told ahead of time of any operation that could endanger British lives. He declined to place a number on the British dead but UK government sources say more than a dozen were killed.

“We were disappointed not to be informed of this in advance…I offered UK technical and intelligence support – including from experts in hostage negotiation and rescue - to help find a successful resolution. And I urged that we and other countries affected should be consulted before any action was taken,” a forthright Cameron said.

At least 30 hostages, several Westerners among them, are now thought to have died in Thursday’s assault along with at least 11 of their captors, although some reports say as many 18 militants were killed.

The Algerians insist they had no choice but to mount the assault, arguing the militants were in the process of leaving the facility and moving their hostages and were intending to blow up part of the facility. “An important number of hostages were freed and an important number of terrorists were eliminated, and we regret the few dead and wounded,” Algerian Communications Minister Mohamed Said Oubelaid told his country’s national media.

Some of the freed hostages agree the assault should have been mounted. Four unnamed Britons interviewed by Algerian television have praised the rescue mission with one saying the Algerian security forces did “a fantastic job.” A second man said: “The gendarmes kept us all nice and safe and fought off the bad guys.”

Other freed and escaped hostages who have spoken of their ordeals have been more focused on coming to terms to what they endured in the siege rather than debating the rights and wrongs of the assault.

A 27-year-old radio operator at the facility, Azedine, admitted he was still in a state of shock after escaping. He says he stayed in his office when the militants first stormed the complex, hiding quietly for several hours to avoid capture. “I stayed silent a couple of hours waiting for the light of day. I saw the terrorists; some were clean, others were dirty, some with beards, others without, and among them a French national with sunglasses. He looked European.”

Algerian officials have not mentioned any Europeans among the militants but have said the fighters were drawn from a variety of countries, including Egypt, Algeria, Tunisia and Libya.

Speaking to French television, Azedine said he saw the corpse of his French supervisor. “My supervisor was a great man; I learned a lot from him. He had been shot, but I did not see the execution. All I saw was his body when I ran with some colleagues to leave the base…we are very lucky, but the face of my French supervisor is still before my eyes.”

He wasn’t the only one who did his best to stay out of the clutches of the militants. Talking to Europe 1 radio, Alexandre Berceaux said he hid for 40 hours underneath the bed in his living quarters. “I was afraid. I could see myself ending up between four planks of wood” – in a coffin…I saw some dead,” said Berceaux.During the early hours of the siege, witnesses say the militants stared to rig the complex with explosives and noted the fighters were armed also with mortars and anti-aircraft missiles.

And it wasn’t only buildings that were being rigged with explosives. One of the foreign hostages freed in Thursday’s assault told his family that his captors tied explosives around his neck. Talking to the Irish Times, the family of Stephen McFaul, a Belfast electrician, say he managed to flee when the vehicle he was in crashed after coming under attack from Algerian forces.

According to his mother he phoned her on the first day of the hostage crisis. “He phoned me at 9 o'clock to say Al Qaeda were holding him, kidnapped, and to contact the Irish government, for they wanted publicity,” she told the Irish Times. The 36-year-old father-of-two saw four jeeps full of hostages blown up by Algerian troops.

Two Turkish workers and a colleague from the Philippines cut a hole through a metal fence to escape the compound during the Algerian army assault. “As bullets rang out nonstop, we cut holes in the metal fence with large clippers, and once through, we all started running,” an Algerian driver, Brahim, told France 24. “We were quickly taken in by the special forces stationed just a dozen meters from the base. I didn’t look back.”

Several witnesses say security at the facility had not been heightened in the days following French military intervention in neighboring Mali, the motive the militants give for their hostage taking.But terrorism experts believe the operation must have been planned long before France deployed troops in Mali.

“This was a highly organized and carefully designed operation that would have taken months in the planning,” says Andrew Black, who has studied for the Washington DC-based think tank, the Jamestown Foundation, the group’s overall leader Mokhtar Belmokhtar.

The militants had considerable knowledge of the huge energy facility, knowing its layout in detail, and U.S. security sources say the group of fighters who were dispatched by Belmokhtar took a circuitous route via Libya from north Mali into Algeria to take advantage of the instability in Libya to pass undetected.

Black draws comparisons with previous large-scale operations mounted by Belmokhtar and his allies, including the hostage taking of more than 32 European tourists in 2003 in Mauritania. “His operations blend military and PR dimensions and his objective always includes garnering publicity for himself which helps boost his stature among Jihadists.”

And the remaining militants appear eager to milk the crisis right to the bitter end. Now they say they are ready exchange the hostages they still hold for two terror figures currently in jail in the U.S. The militants want the release of Egyptian Sheikh Omar Abdel-Rahman and Pakistani Aafia Siddiqui. Serving a life sentence in North Carolina for masterminding the 1993 attack on the World Trade Center in New York City, Abdel-Rahman, also known as the “Blind Sheikh,” is an iconic figure for Jihadists.