The fate of the suspected mastermind of the Paris attacks, Abdelhamid Abaaoud, is still unknown after a huge police raid left at least two dead.
It came as it emerged the US warned months ago he could be planning an assault.
Police staged a ferocious seven-hour assault in the north of Paris on Wednesday after intelligence led investigators to a flat where the Belgian suspected of orchestrating the worst ever militant attack on French soil was thought to be hiding.
At least two people were killed in the raid – a woman thought to have blown herself up with a suicide vest and another body that was found riddled with bullets – according to Paris prosecutor Francois Molins.
Eight people were arrested, but neither Abaaoud nor 26-year-old Salah Abdeslam – suspected of taking part with his suicide-bomber brother Brahim in the attacks last Friday that killed 129 people – were among those held.
French MPs will on Thursday begin debating whether to extend the state of emergency declared after last week’s attacks by three months to February, and expand it to allow suspects to be placed under house arrest.
Molins said the raid had thwarted a “team of terrorists that … could have struck”.
Police rained more than 5000 rounds of ammunition on the building after terrified residents living in the area near the Stade de France stadium were evacuated.
A series of explosions rang out as the police closed in on the dwelling and one suspect was seen being dragged away, his bare buttocks exposed.
Severe damage to the building and the state of the bodies found inside made it impossible to know exactly how many people had been killed and who they were, the prosecutor said.
As details were still emerging of the shootout, US intelligence published a report showing it warned in May that IS was capable of carrying out the kind of large-scale, coordinated attacks seen in Paris.
The assessment from the Office of Intelligence and Analysis, in co-ordination with the FBI, specifically refers to Abaaoud as a ringleader of Belgian plotters and warned Europe was more at risk of attack than the US.
Abaaoud is a 28-year-old Islamic State fighter who was previously thought to be in Syria after fleeing raids in his native Belgium earlier this year.
Seven jihadists were killed or blew themselves up in Friday’s attacks and several European countries have launched an international operation to hunt down any other plotters.
In Sweden, police Wednesday were hunting for a man suspected of “planning a terrorist act”, who media reported was an Iraqi who had fought in Syria.
IS, meanwhile, released a new video threatening New York, and specifically Times Square, although police said there was no “current and specific” threat.