French police fired five thousand bullets during a ferocious seven-hour kill-or-capture operation in which the mastermind of the Paris attacks is believed to have been shot dead.
A dawn raid on an apartment block in the Paris suburb of Saint-Denis was so violent that police must wait for the results of DNA tests to identify the remains of two terrorists who were killed.
But the Washington Post claims two intelligence sources have confirmed one of the dead is Abdelhamid Abaaoud.
Until Tuesday, the French security services assumed the only way to neutralise Abaaoud was through airstrikes on Raqqa, because he was believed to be in Syria, where he had become one of ISIL's most high-profile recruiters.
But then the investigation into the murders of 129 people took an astonishing turn: witness accounts and information found on a discarded mobile telephone suggested Abaaoud was not in Syria, but had all along been holed up in an apartment in Saint-Denis, just a few minutes away from the Stade de France.
Worse still, it appeared he was controlling another terrorist cell preparing for a fresh wave of attacks on Paris.
A vital new lead came from a mobile phone thrown into a bin by one of the terrorists who attacked the Bataclan concert hall on Friday night. The last text message sent from it, at 9.42pm, just as the assault on the Bataclan was starting, said: "Off we go, here we go again." Analysis of the phone's content and its GPS tracker led police not only to a safe house in Alfortville, in the south-east of Paris, but also suggested Abaaoud was in Saint-Denis. A female cousin of Abaaoud, Hasna Aitboulahcn, was placed under surveillance on Tuesday, and at 4.20am local time yesterday (03.20GMT), when police assumed their targets would be at their most vulnerable, they moved in with lethal force to the building where she and Abaaoud were believed to be hiding.
Officers from the elite RAID anti-terrorism unit - many of whom had been in action during the attacks on Friday - moved into the apartment block in Rue du Corbillon hoping to blast their way into the suspects' third-floor flat and capture them before they could react.
But their way was barred by a reinforced door which held out against the explosive charges placed against it. What had been planned as a lightning raid was about to turn into one of the fiercest gun battles on French soil in decades. The sound of automatic gunfire woke the residents in the next street, Rue de la Republique, and the surrounding area as police exchanged shots with the terrorists.
At 4.45am, police got their first breakthrough, when they gained control of a second suspect apartment and arrested three men inside.
But the main target flat was proving impossible. As officers struggled to gain control, Diesel, a seven-year-old German Shepherd police dog, was sent into the building at 5am to tackle the terrorists, only to be shot dead.
Stephane Colas, 41, who lives near Rue de la Republique, said: "I was woken at about 5am by a police helicopter going round and round. I went outside to see what was happening and the police were going house to house. They were saying 'evacuate, evacuate'."
Aitboulahcn appeared at a window, shouting "help me, help me", perhaps to lure the police in. She was told that if she did not stay where she was, she would be shot, but went back inside.
At around 6am, police began a fresh assault. Their targets were ready for them, wearing their suicide vests. Aitboulahcn was the first to open fire during the fresh exchange, using a Kalashnikov assault rifle.
The police tried to talk to Aitboulahcn, asking her: "Where's your boyfriend?" "He's not my boyfriend!" she screamed in reply.
Seconds later, she detonated a suicide vest, killing herself and causing the floor of the apartment to collapse. The explosion was so violent that her spine was later found lying in the street outside. A second terrorist, believed to be Abaaoud, was killed in the battle that ensued, after being "riddled with bullets" and hit by fragments from a grenade.
Unsure how many more terrorists were in the building, the police fell back, and for the next three hours Saint-Denis was the location of a siege.
Francois Molins, the Paris prosecutor, said: "It was an extremely difficult assault, because the armoured door did not give way straight away to police explosives, thus allowing the terrorists to prepare their riposte. Very heavy, almost uninterrupted gunfire ensued for almost an hour. On the police side we fired almost 5,000 munitions."
Residents of Rue de la Republique and La Rue Corbillon were told to stay indoors as a police cordon was set up around the apartment building. Then a small robot equipped with a camera, similar to those used in bomb disposal, was sent into the flat to check if anyone was still inside.
"It's as if war has come to our neighbourhood," said Mohamed Diallo, 22. "It's like a siege. People haven't gone to work and everyone is keeping the children at home."
At around 7.30am local time, a series of explosions signalled the start of another assault by the police, now numbering 110 specialist officers.
Five or six explosions were heard, followed by a 90-second pause, then another half dozen blasts. Police had discovered that two suspects were hiding in the debris caused by the initial assault and suicide bomb, and managed to take them alive. One of those arrested was brought out naked from the waist down, suggesting he had been ordered to strip off by officers to prove he was not wearing a suicide belt. Inside the flat was a wealth of evidence that showed another terrorist attack had been foiled. Weapons, explosives, suicide vests and plans were among the items seized.
With no time to lose, police began questioning the three men arrested in the flat, to establish what they had planned and whether other suspects were still at large. They had reportedly been planning a fresh wave of attacks against La Defense, the financial district of Paris, and Charles de Gaulle airport, Europe's second-busiest. Mr Molins said: "Everything leads us to believe that given their weaponry and level of preparation, they were ready to act."
Jawad Bendaoud, the owner of the flat, was speaking to reporters when he was arrested. He said: "A friend asked me to let the house to his mates for a couple of days. I was asked to help people out. I had no idea who they were. I don't know them from Adam."
His friend told him the men were coming from Belgium and needed a place to stay for a couple of days. "I told them there were no mattresses and they said 'That's OK,' they just wanted water and a place to pray," he said.
A friend of Mr Bendaoud - who was sentenced to eight years in prison for killing his best friend in a fight in 2006 - said she had slept in the apartment last week and it was a "sort of squat".
Meanwhile, police feared the top-floor flat could have been booby trapped with explosives, or that other terrorists were still hiding there.
For the next three hours police planned their next move, evacuating all residents of the block and checking their backgrounds to check for any possible links to the terrorists.
Just after 11.30am local time, police confirmed that the operation was over. The apartment building was so badly damaged that it had to be shored up before forensic teams could move in.
Two men and a woman were arrested nearby, bringing the total number held to eight, including Mr Bendaoud.
Bernard Cazeneuve, the interior minister, paid tribute to the police who have "never before come under such gunfire". Five officers were injured.
Francois Hollande, the French president, described the raid as "a particularly perilous and heavy police operation", and paid tribute to police who "knew the dangers, yet no doubt still underestimated the violence that they would come up against".