Although the suspected organizer of the Paris attacks that killed 129 people is dead, a security adviser to President François Hollande said Thursday that "we think we are just in the middle of the storm."
But the death of the alleged organizer of the attacks, Abdelhamid Abaaoud, 27, during a raid in Saint-Denis early Wednesday could delay plans for more terror attacks, Alain Bauer, the French president's adviser on security, told NBC News in an interview.
"The [ISIS] caliphate will need some time to find ... not other people ready to die, or other terrorist ready to act, but a supervisor is much more complicated than a jihadi or a shahid, which is a name for martyrs," Bauer said.
France tried to kill Abaaoud in an airstrike in Raqqa, Syria, on Oct. 8, more than a month before the attacks on Paris on Nov. 13, Bauer said.
"Military intelligence knew perfectly that he was preparing something huge and extremely dangerous," Bauer said.
Abaaoud, a Belgian jihadi who once boasted of being able to evade Western intelligence, has been linked to at least four of six foiled attacks this year, French officials said.
French officials believe Abaaoud was in France soon after the Paris attacks because in previous plots he was close to the scene — and he may have been planning a further attack, Bauer said.
"He is a player that wants to see it (the outcome of his plotting)," Bauer said.
French authorities are searching for others that may have been involved in the attacks and a manhunt is underway for suspected accomplice/driver Salah Abdeslam, 26.
During the attacks in Paris, most of the attackers used suicide belts and vests to blow themselves up, and French officials have said the explosive devices contained the explosive TATP.
On Thursday, an analyst told a U.S. Senate Homeland Security Committee that the use of TATP (triacetone triperoxide) — which can be made with household goods like hair dye, but is very volatile — suggests someone with "real training" prepared the bombs.
"To make an effective TATP bomb requires real training, which suggests a relatively skilled bomb maker was involved in the Paris plot, since the terrorists detonated several bombs," Peter Bergen, director of nonpartisan think tank New America Foundation's international security and future of war programs, said according to written testimony.
TATP was used by the so-called "shoe bomber" Richard Reid, who unsuccessfully tried to detonate explosives on a jet in 2001. Traces of the explosive were also found in detonators used in bombs during a planned attack on London's public transportation system in 2005, The Associated Press reported at the time.
Bergen said the use of TATP in the Paris attacks "also suggests that there was some kind of bomb factory that, as yet, appears to be undiscovered, because putting together such bombs requires some kind of dedicated space."
On Wednesday, a person sought by French police under a state of emergency following the terror attacks in Paris turned himself in to authorities in Lille, days after the search of an apartment in which explosives were found, a police official said.
The duty officer at the police station in Lille confirmed that a house was raided Sunday night or early Monday in the neighborhood of Hem after police received a tip about a suspect.
That person was not at the apartment, but two others were there and they were arrested, and explosives were found, the police official said.
On Wednesday, the suspect being sought surrendered to police in Lille, but it was unclear how he was connected to the ongoing investigation.