An explosion "wiped out" four of the vehicles, while McFaul's vehicle crashed. He was able to get out and, eventually, contact his family.

"I haven't seen my mother move as fast in all my life, and my mother smile as much, hugging each other," Brian McFaul of Belfast, Northern Ireland, said upon his family hearing his brother was safe. "... You couldn't describe the feeling."

Al Qaeda-linked group offered prisoner-hostage exchange

A spokesman for Moktar Belmoktar, a longtime jihadist who leads the Brigade of the Masked Ones -- a militant group associated with al Qaeda in the Islamic Maghreb -- reportedly offered to free U.S. hostages in exchange for two prisoners.

Behind the group claiming responsibility for the attack and kidnappings, he is known for seizing hostages and has long been targeted by French counterterrorism forces.

The prisoners are Sheikh Omar Abdel Rahman, who orchestrated the 1993 World Trade Center bombing, and Aafia Siddiqui, a Pakistani woman jailed in the United States on terrorism charges, the spokesman said in an interview with a private Mauritanian news agency.

Nuland rejected the offer, restating U.S. policy of not negotiating with terrorists.