Charlie Hebdo
© AFP Photo / Thomas SamsonRescue service workers and firefighters gather near the site of a shooting on the morning of January 8, 2015 in Montrouge, south of Paris.
The deadly events that unfolded in France over the last week may be the first in a wave of attacks to strike Europe, a German daily reports, citing NSA intercepts of communications between Islamic State (IS, formerly ISIS/ISIL) leaders.

Paris was marked as the first in a series of European cities to be attacked, including Rome, the report in the German tabloid Bild read. However, the article didn't furnish details of a concrete plan to launch an attack.

The US National Intelligence Agency (NSA) also reportedly had information that Cherif and Said Kouachi, the brothers who carried out the mass shooting at the French satirical weekly Charlie Hebdo, had contacts in the Netherlands.

Police were said to have been put on high alert after intelligence learned that Amedy Coulibaly, the terrorist who killed a policewoman on Thursday in Paris and another four people in a kosher supermarket in Vincennes on Friday, may have activated sleeper cells which aim to attack law enforcement, CNN reported
Charlie Hebdo
© AFP Photo / Bertrand GuayA man holds a cardboard reading "Hommage to the Victims-Heros" as people gather on the Place de la Republique (Republic Square) in Paris before the start of a Unity rally “Marche Republicaine” on January 11, 2015.
In a slickly produced video released online, Coulibaly swears allegiance to "Caliph Ibrahim", also known as Abu Bakr al-Baghdadi, the self-proclaimed IS leader.

When asked by an unidentified interviewer if he had any links to Cherif and Said, Coulibaly responded:

"The brothers of our team were split into two groups...I went out a bit against the police."

Despite Coulibaly's declared allegiance to IS, Cherif had earlier claimed he was trained and financed by Al-Qaeda in Yemen.

On Saturday, one of the Al-Qaeda leaders in Yemen, Harith al-Nadhari, posted a video online threatening France with vengeance.

"Soldiers who love Allah and are His messengers are amongst you," he said.

"They do not fear death. They seek martyrdom in the name of Allah."

Charlie Hebdo
© AFP Photo / Joel SagetPeople gather at the foot of the centrepiece of Place de la Republique, a statue of Marianne, in east Paris on January 11, 2015 prior to a huge march.
Police are still searching for Hayat Boumeddiene, the girlfriend or possibly wife of Coulibaly. Although the 26-year-old had initially been described as being armed and dangerous, security sources later said that she wasn't in France at the time of the attacks.

Police initially suspected Boumeddiene may have played a role in organizing the Paris attacks. Turkish security sources, however, told AFP that she arrived in Turkey on January 2, and had since likely moved on to Syria.

At least 20 people, including the three attackers, were killed in a spate of attacks in and around Paris this week.

Following the bloody culmination of events on Friday, French President Francois Hollande warned that the threats facing France were not over.