"Providing money, personnel and services"

Holder said four separate indictments unsealed in various locations charge the 14 "with terrorism violations for providing money, personnel, and services" to the group.

The indictments "shed further light on a deadly pipeline that has routed funding and fighters" to the Shabaab, Holder said.

Two of those charged were arrested earlier in the day in Minnesota, officials said, including one man and one woman accused of raising money for the Shabaab on the pretense of collecting funds "for the poor and needy."

Several of those named in the new indictments had been previously charged by U.S. authorities, and several are believed to be overseas, likely in Somalia where they may be fighting for the Islamist group.

Holder said the latest charges were part of a broader investigation that had charged a total of 19 people, of whom nine had been arrested in the United States or abroad.

"Ten of the charged defendants are not in custody and are believed to be overseas," he said.

One indictment unsealed Thursday in Minnesota charges 10 men, including at least three U.S. citizens, with terrorism offenses for leaving the United States to join the Shabaab as foreign fighters, he added. Seven of these had been previously charged by either indictment or criminal complaint.

Providing material support

Also in Minnesota, FBI agents arrested Amina Farah Ali, 33, and Hawo Mohammed Hassan, 63, both naturalized U.S. citizens from Somalia. The woman and man are charged with conspiracy to provide material support to the Shabaab.

In two separate cases, two U.S. citizens were charged in separate cases with providing material support to the Shabaab. Both are believed to be in Somalia.

The Shabaab, an Islamist extremist group that controls most of central and western Somalia, claimed responsibility for the attacks in Uganda's capital on July 11 that killed 76 people gathered to watch the World Cup final.

Earlier media reports said 14 Americans had been arrested in the probe.

Holder said the Justice Department would continue to pursue cases of so-called homegrown terrorism involving Americans joining foreign extremist groups.

"As demonstrated by the charges unsealed today, we are seeing an increasing number of individuals -- including U.S. citizens -- who have become captivated by extremist ideology and have taken steps to carry out terrorist objectives, either at home or abroad," he said.

"It's a disturbing trend that we have been intensely investigating in recent years and will continue to investigate and root out. But we must also work to prevent this type of radicalization from ever taking hold."

Alabama, California, Minnesota

In Alabama, prosecutors unsealed a September 2009 superseding indictment against Omar Hammami, 26, a U.S. citizen accused of providing material support to the Shabab. He is believed to be in Somalia.

In California, officials today unsealed an October 2009 indictment against Jehad Serwan Mostafa, 28, a U.S. citizen also believed to be in Somalia, on similar charges.

In Minnesota, 10 others were named in indictments in addition to the two arrested Thursday. They include three U.S. citizens and four legal U.S. residents, all of whom are believed to be overseas.

Among those named are U.S. citizens Abdikadir Ali Abdi, 19, Abdisalan Hussein Ali, 21, and Cabdulaahi Ahmed Faarax, 33; Farah Mohamed Beledi, 26, and Abdiweli Yassin Isse, 26. They are charged with conspiring to kill, maim and injure persons abroad and other charges.

Five others who had been previously charged by indictment, on related charges, are Ahmed Ali Omar, 27; Khalid Mohamud Abshir, 27; Zakaria Maruf, 31; Mohamed Abdullahi Hassan, 22; and Mustafa Ali Salat, 20.

The announcement came a day after a U.S. man was arrested hours before he was scheduled to travel to Somalia to fight with the Shabaab.

Shaker Masri, 26, was charged with attempting to provide material support to two U.S.-designated terror organizations, al-Qaeda and the Shabaab.