At one point, authorities believe he was holed up on the third floor of an apartment building in the northern Paris suburb of Saint-Denis, Paris prosecutor Francois Molins said Wednesday. Whether he was there when scores of heavily armed French police launched their assault at 4:20 a.m. Wednesday (10:20 p.m. ET Tuesday) is unknown.
Some residents in the area told CNN they saw Abaaoud recently in the neighborhood and at a local mosque.
Investigators zeroed in on the building after picking up phone conversations indicating that a relative of Abaaoud might be there. They met fierce resistance from the start, including an armored door, a woman who blew herself up and bullets flying back and forth for about an hour. The French officers even used powerful munitions, which led to one floor of the building collapsing.
That violence produced rubble that included body parts, on which investigators are conducting DNA tests.
Neither Abaaoud nor suspect Salah Abdeslam
, for whom authorities have been hunting since the attacks, were among those detained in the operation, Molins said.
French President Francois Hollande held up the vicious back-and-forth as further proof that "we are at war" with ISIS.
"What the terrorists were targeting was what France represents. This is what was attacked on the night of November 13," he said. "These barbarians targeted France's diversity. It was the youth of France who were targeted simply because they represent life."
first drew international attention for taking over swaths of Iraq and Syria, leaving a trail of violence and destruction in its wake. And its efforts to bring terror to the global stage seem to be growing. This month alone, ISIS has claimed responsibility for the Paris attacks, the downing of a Russian passenger jet in Egypt and a pair of suicide bombings in Beirut.
France had already been part of the U.S.-led coalition fighting ISIS with airstrikes. But the country has stepped up its efforts since the series of shootings and explosions in Paris last week, which killed 129 people.
Now, Hollande has proposed extending France's state of emergency for three more months -- a measure that, among other things, gives authorities greater powers in conducting searches, holding people and dissolving certain groups. To go after the Islamist extremist group, the French President also said he would appeal to world leaders -- including meeting next week with U.S. President Barack Obama and Russian President Vladimir Putin, who have been at odds on what to do in Syria.
"There is no more ... divide. There are only men and women of duty," he said. "We must destroy this army that menaces the entire world, not just some countries."
'We could see the bullets'
Whoever was inside the Saint-Denis apartment on Wednesday appeared to be "prepared to act" in possibly another attack, Molins said, noting their weaponry, structured organization and determination.
Some 110 police swarmed on the diverse, working-class area that is home to the Stade de France sports stadium, where three suicide bombings took place days earlier.
They first went into one apartment that had been under surveillance since Tuesday, a Paris police source said.
Telephone communications on a wiretap by French and Belgian security agencies indicated a woman at the residence was Abaaoud's cousin, a Belgian counterterrorism official told CNN.
That raid led them to another apartment on the same street. Molins described it as a complex operation. For almost an hour, he said, there was uninterrupted gunfire as police tried to get into the apartment.
The violent standoff left residents in the area, already shaken by last week's attacks, startled and scared.
"We could see the bullets," a woman, who identified herself only as Sabrine, told CNN affiliate France 2. "We could feel the building shaking."
Three people in the Saint-Denis building itself, including one with a bullet wound in the arm, are among the eight detained, according to Molins. The others include the person who loaned the apartment to the suspected terrorists and his friend. Two of the eight held were hospitalized, Interior Ministry spokesman Pierre-Henry Brandet told France Info radio.
Five French officers, meanwhile, were slightly wounded, while a police dog died in the operation
, according to police.
Saadana Aymen, a 29-year-old who lives one street down, couldn't believe what was happening in his neighborhood.
"When you think of Saint-Denis, you don't think of terrorists," he told CNN. "I'm shocked! Why would the terrorists pick this neighborhood?"
Will phone offer clues?
That wasn't the only place where French authorities fanned out Tuesday night into Wednesday as they worked to find suspects tied to the attacks and cracked down on security.
The Interior Ministry announced 118 searches led to the detention of at least 25 people, the confiscation of 34 weapons and the discovery of illicit drugs in 16 instances. In recent days, hundreds of similar operations have been conducted, the ministry said, resulting in 64 people being held and 118 put under house arrest.
Authorities have not provided details about the arrests or said what connection they could have to Friday's attacks.
Molins said investigators are working to piece together where terrorists were in the days and hours leading up to the attacks -- and with whom they had contact.
They've encountered at least one piece of evidence that could help them in their search: One of the attacker's cell phones was found in a trash bin outside the Bataclan theater, where most of Friday's victims were gunned down.
A message on the phone, according to Molins, said, "Here we go, it's starting."
Authorities are trying to determine who the message was sent to, he said.
And they're still trying to determine whether the suspected ringleader in the attack is still on the run, or whether his remains were found in the rubble.