Said Kouachi, one of the two gunmen involved in last week's massacre at the offices of the French satirical newspaper Charlie Hebdo in Paris, once told a Yemeni reporter that he had lived with Umar Farouk Abdulmutallab, the Nigerian "underwear bomber" behind the failed 2009 terror plot on a Detroit-bound airliner.

Mohammed al-Kibsi, the Yemeni journalist, told the Associated Press that he met Kouachi in early 2010 in Sanaa, Yemen's capital, where Abdulmutallab — who was later convicted of trying to blow up the Northwest Airlines flight on Christmas day 2009 using explosives concealed in his underwear — was studying Arabic.

Al-Kibsi said he asked Kouachi if he knew Abdulmutallab.

"Surprisingly, he said that, 'Yes,' he knew him and that he lived with him in the same residence," al-Kibsi said Monday. "(Abdulmutallab) had left three or four months before we met Said."

Said Kouachi told al-Kibsi that he and Abdulmutallab prayed together at Yemen's al-Tabari School and studied Arabic at the Sanaa Arabic Grammar Institute. The pair shared an apartment "for one to two weeks" in Yemen, al-Kibsi said.

Kouachi described Abdulmutallab as "a very quiet person" who "rarely talked to people," al-Kibsi told CNN.

Said Kouachi, 34, and his 32-year-old brother, Cherif Kouachi, both French nationals, were killed after a massive manhunt and subsequent standoff with police in northern France on Friday, two days after they killed 12 people in an attack on Charlie Hebdo's offices. Amedy Coulibaly, an associate of the Kouachis, killed hostages inside a kosher grocery store in a Paris suburb before he was killed during a police raid.

The journalist described the elder Kouachi as "very polite," with "a sense of humor."

"I could not expect that a few years later he would be the suspect of a terror attack," al-Kibsi said. "When I first met him he was wearing a track suit, playing football with kids in the street."

The AP reported that Abdulmutallab had told U.S. investigators he trained in Yemen and targeted the U.S.-bound flight at the urging of Anwar al-Awlaki, a radical, American-born Muslim cleric who was killed in a U.S. drone strike in Yemen in 2011. Al-Awlaki's commentary was featured in Inspire magazine, al-Qaida's English-language publication, which encourages readers to carry out "lone wolf" attacks on Western targets.

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Al-Kibsi said he did not know whether Kouachi had met al-Awlaki while he was in Yemen.

Last week, U.S. officials said they believe Kouachi spent several months in Yemen in 2011 receiving weapons training and working with al-Qaida in the Arabian Peninsula. A senior Yemeni national security official told CNN that Said Kouachi entered Yemen multiple times with a legal visa and was not being watched.

Last week, U.S. counterterrorism officials told Yahoo News that the Kouachis were on a "no fly" list that banned them from boarding commercial aircraft going into and out of the United States.

On Monday, U.S. officials told CNN that Coulibaly was "known" to them before the Paris attacks, though it's unclear why. Before he was killed by police, Coulibaly reportedly told a French television station that he was a member of the radical group Islamic State.

French authorities are now searching for Hayat Boumediene, Coulibaly's common-law wife, as well as other possible accomplices involved in last week's attacks, fearing that they are part of a larger terror cell.

"The threat is still present," Prime Minister Manuel Valls told a French television station, according to CBS News. "We consider that there are most probably some possible accomplices," Valls told BFM television.