(CNN) -- The militants carrying out a terrorist attack at a mall in Kenya include American teenagers, the Kenyan government says.
There's no question Al-Shabaab, the group behind the attack, has recruited young Americans. The group has released videos of some going through training camps, including one in which an American declares it "the real Disneyland," CNN affiliate WCCO reported in August.
But just who the perpetrators are of the Nairobi mall attack remains unclear. More than 60 people have been killed.
"Both the victims and the perpetrators came from Kenya, the United Kingdom, and the United States," Kenyan Foreign Minister Amina Mohamed told "PBS NewsHour."
The information she had indicates two or three Americans and one British woman are involved, Mohamed said.
"The Americans, from the information we have, are young men, about between maybe 18 and 19."
They are of Somali origin, but lived in Minnesota or other parts of the United States, she said, adding that underlines "the global nature of this war that we're fighting."
U.S. officials have not confirmed that Americans are involved in the attack, deputy national security adviser Ben Rhodes said Monday.
Al-Shabaab released names of people who it said were perpetrators. U.S. officials were looking into the names, a senior State Department official said.
"We do know that 40 to 50 Americans have gone over there to join what they call 'the fight,'" Rep. Michael McCaul, Republican chairman of the Homeland Security Committee, told CNN.
"Certainly, it's very plausible that three of (the attackers) could have been Americans."
The United States has been tracking recruited Americans for several years "to try to get the identifying travel information, to ensure that these Americans don't come back into the United States, and if they do, they'll get picked up immediately at our airports," McCaul said.
Mohamed, speaking to PBS, said the attackers' nationalities are ultimately irrelevant. "They are all evil," she said. "and we must deal with them as such."