French law enforcement agencies have told police to carry arms at all times and take down their presence in social media as terror cells have been activated across France over the weekend, a U.S. cable network reported.

One of the suspects killed in an attack on a kosher market in Paris, Ahmedy Coulibaly, was overheard as saying while making a phone call to target French police, CNN said.

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France has been coping with three days of terrorist attacks that killed 17 people. A million unity sympathizers are expected to pour into Paris streets on Sunday, along with European and Middle East leaders and other dignitaries.

The Kouachi brothers, who were suspects in Wednesday's massacre in the offices of satirical magazine Charlie Hebdo, were killed on Friday in a gunfire exchange with French security forces in the suburbs of Paris.

A French-language magazine reported that police initially had the Kouachis under their watch. Despite red flags, authorities lost interest in them. Reports said U.S. intelligence agencies tipped off the French that Said Kouachi may have visited Yemen in July last year. In November 2011, France placed him under watch but ended the surveillance in June last year when security services concluded he no longer posed a threat.

The monitoring of Said's brother Cherif was wrapped up in 2013 when his phone calls indicated he was focused on faking clothing and shoes instead of violent extremism. Intelligence officials said there is a big chance Cherif Kouachi separately visited Yemen in 2011.

Kouachi stayed in Yemen several times with an official visa, a senior Yemeni national security official told a U.S. network. He said Kouachi was not watched during his visit in Yemen because he was not on any watch list. He not say when the visits happened. 

TagsParis, Charlie Hebdo massacre, Terror Cells, islamic extremists, 'Je suis Charlie'