(NBC NEWS) -- U.S. officials are looking hard into allegations that Americans were among the attackers at the Westgate Mall in Nairobi.
There is no confirmation that Americans were involved in the attack, but U.S. officials say the group has successfully recruited Americans in the past.
At least 62 people have been killed since gunmen stormed the crowded mall Saturday. Kenyan authorities say they've got the upper hand, but there was gunfire overnight.
As of this morning, Kenya reports that several attackers have been killed, and more arrested for questioning.
Kenya's Foreign Minister says some of those involved were Americans. "The Americans, from the information we have, are young men, about between maybe 18 and 19," said Kenyan Foreign Minister, Amina Mohamed.
But U.S. authorities say they won't know for sure until all the attackers are identified.
Names provided so far were not on any terror watch lists. "It could be very likely that there were Americans involved in this attack because there is a significant number of them that have gone over there to be trained," said Rep. Peter King, (R) New York.
About 20 are now believed to fighting in Somalia with the terrorist group al Shabaab which claims to be behind the mall attack.
The group's been recruiting hard in Minnesota. Muslims there condemn the violence. "We call on Muslim youth to shun and reject or to be lured into or recruited by extremist groups like al Shabaab," said Minnesota Muslim Leader Abdisalam Adam.
"This is a global challenge for the U.S.," said the Former Ambassador to Morocco Marc Ginsberg.
President Obama is promising to help in the investigation of what happened and who was behind it.
Authorities tell us al Shabaab has made vague references to attacks in the U.S., but officials here think that's mostly propaganda.