The guns are quiet, but the dead are still to be counted

The horror at In Amenas ended as dramatically as it began, and as bloodily

The Algerian hostage crisis ended yesterday as it had begun, in a jolting surge of bloodshed that left both innocent and guilty dead. Special forces stormed the In Amenas gas complex, and killed the remaining 11 attackers, but not before seven foreign hostages were shot, reportedly executed by the terrorists.

As night fell, Algerian troops were inside the complex clearing it of mines and booby-traps planted by the attackers. They had, however, yet to discover the fate of all the 20 to 30 foreign hostages who were still being held there yesterday morning. Earlier in the day, troops entering the refinery had found 15 charred bodies, whose identities are still not known, while some 16 hostages – including two Americans, two Germans and one Portuguese, but not Britons – had been freed before the final assault began.

Last night, the Algerian government said that, in total, 23 hostages and all 32 terrorists had died during the attack and siege, while 107 foreign workers and 685 local employees had been released, or escaped.

When yesterday dawned, with the Algerian army still surrounding the complex, helicopters hovering overhead and ambulances waiting near by, it seemed likely that the endgame was just hours away. No more than 12 terrorists were still inside the refinery part of the complex, their varying demands had been rejected, and they were believed to have with them large amounts of plastic explosives. The entire refinery was mined with explosives and booby-traps, the state oil company Sonatrach said in a statement, and Algerian media reported that the militants had planned to blow up as much of the complex as they could. At mid-morning, a fire broke out in the plant, and Algerian special forces went in.

Thus ended the worst Western hostage crisis for years. It had begun around 5am on Wednesday. Two buses were carrying foreign workers from the In Amenas gas field to its airport 30 miles away, and, as usual, their drivers were in contact via a walkie-talkie with the complex's communications room. A radio operator, Azedine, said: "Moments after the bus left, I heard shooting, a lot of shooting, and then nothing." A group of terrorists, believed to number around 30, had attacked. The military escort returned fire, bus passengers threw themselves to the floor as the bullets zinged over their heads, and the attack was beaten off. A Briton and an Algerian, probably a security guard, were killed, but other bus passengers climbed out of a window and were taken to a nearby military camp.

Thwarted, the terrorists turned to the vast gas complex, whose refinery and workers' living quarters are both hundreds of yards wide, and entered it in three vehicles. Freed hostages later spoke of an alarm being raised, power being cut, and frightened people hunkering down in their offices or accommodation. Some hid – two Britons concealed themselves in a canteen's false ceiling; others lay flattened on a roof. And a French hostage employed by a French catering company said he had hidden in his room for 40 hours under the bed before being rescued by Algerian troops.

Terrorists began taking hostage any occupants they could find, dividing them into foreigners, of whom there were 132, and Algerians, numbering at least 650. Others they shot, like the French supervisor whom the radio operator Azedine saw killed by a gunman, who then took the ID badge of his victim and put it around his neck.

Almost immediately, the Algerian army was on the scene. An army barracks housing hundreds of soldiers lies on the two miles of road separating the two parts of the complex, and as the morning went on, tanks, helicopters and heavy arms arrived. There was no possibility of escape. Neither, given the Algerian experience of dealing with a lengthy Islamic insurgency which has cost 200,000 lives and their Russian anti-terrorist training, was there much chance of protracted negotiation. There are reports of some firing on Wednesday night, but it was on Thursday, about 30 hours after the siege began, that Algerian troops moved in – prompted, commanders said, by the gunmen's demand that they be allowed to take their captives abroad, almost certainly to Mali.

No coherent narrative of events is available, but escaped, or rescued, hostages, have described sporadic incidents. Mohamed, a 37-year-old nurse, said at least five people were shot dead, their bodies still in front of the infirmary when he left on Thursday night; some foreigners and scores of Algerians escaped, or were released. Among them was Brahim, a driver for BP technicians. He said: "We walked out of the prefabs in which we live, and each tried to find a hiding place. There was a bit of space between the ground and the floor of my quarters, so I crept under there. When night fell, a few colleagues went back into their barracks to sleep, but I spent the night under my quarters, absolutely terrified.

"At about 1pm yesterday, the Algerian army started to attack the terrorists. Despite our fear, as soon as we started hearing the firefight, we decided it was time to try our luck. As bullets rang out non-stop, we cut holes in the metal fence with large clippers and, once through, we all started running. There were about 50 of us, plus the three foreigners. We were quickly taken in by the special forces stationed just a dozen metres from the base. I didn't look back."

The terrorists had filled five jeeps with hostages and, on Thursday, begun to move when Algerian government attack helicopters opened fire, leaving four in smoking ruins, and hostages and gunmen dead. The fifth vehicle crashed, allowing a father of two, Stephen McFaul, 36, from west Belfast, to clamber to safety, the belt of explosive the terrorists had tied to him still strapped around his neck.

The attackers said the operation was a response to the French military action against Islamic insurgents in Mali. That may have made timely propaganda, but yesterday a terrorist spokesman said the attack had been "in the works" for two months. The band of attackers included militants from Algeria, Mali, Egypt, Niger, Mauritania and Canada, he said – a multinational squad that tallies with Algerian reports of the terrorists' bodies so far recovered.

As Thursday drew on, the size of the crisis was absorbed by Western governments. David Cameron abandoned plans for a much-anticipated speech on Europe; Japan's Prime Minister, Shinzo Abe, cancelled a foreign trip; and the phone lines between London, Tokyo, Paris, Algiers and Washington were in almost constant use. Offers of assistance and personnel were made and rejected (not before talks with Washington and Paris), and there were concerns the Algerians might clatter in prematurely and add to the death toll.

As the siege entered its fourth day, accusations that the Algerians were liable to kill first and identify later, seemed unfounded. As far as one can tell, after the shooting up of the vehicles on Thursday, the Algerians' response was far more measured. It was only on Friday that the living quarters were retaken, and it took a fire, and the prospect of the entire refinery being blown sky-high, for the special forces to go in.