French intelligence officials named Abdelhamid Abaaoud as the alleged brain behind the terror attacks and suicide bombings in Paris on Friday that claimed 129 lives. He was also the alleged mastermind of the incident where a man attempted to attack a train in Paris in August but was apprehended by three American men, according to the Advertiser.

Abaaoud, 27, a Belgian extremist of Moroccan origin, has been identified as a known Islamic State fighter and was also connected to a number of past terrorist plots in Europe. He is believed to have close ties with ISIS head Abu Bakr al-Baghdadi. According to Jean-Louis Bruguiere, a leading counterterror judge in the past, the Paris attacks were plotted in Syria and Abaaoud was sure to have been in communication with Baghdadi while the incidents took place on Friday night, according to CNN. 

An unnamed French official said that it was Abaaoud who spoke to a French national coming back from Syria about the ploy of attacking "a concert hall," according to The New York Times. The official added that Abaaoud was in communication with Paris attack suspect Ismaël Omar Mostefaï, and also knew the other suspect, Ibrahim Abdeslam, in 2010 after committing a minor offense together in Belgium.

French Interior Minister Bernard Cazeneuve said authorities have traced and investigated 168 addresses wherein 23 people were taken into custody.

"It's just a start, these operations are going to continue," Cazeneuve said, according to the Guardian. "The response of the Republic will be huge and total. He who targets the Republic will find the Republic will catch him, will be implacable.