Hammami was indicted in the United States on various terrorism charges and is believed to be a senior leader of al-Shabaab, designated by the U.S. State Department as a terrorist organization in 2008.
Hammami was born in Alabama and is now believed to be in Somalia, the FBI said in a statement released Thursday.
Sahiron was indicted on federal hostage-taking charges in connection with the kidnapping of an American in 1993 in the Philippines. The FBI alleges Sahiron is the leader of the Abu Sayyaf group, designated a terrorist organization by the United States in 1997.
The FBI believes he is now in the area of Patikul Jolo, Sulu, Philippines.
Shaykh Aminullah was added to the FBI's Seeking Information -- Terrorism list for his alleged role in providing material support for terrorists.
The FBI said it is believed he provided assistance, funding and recruits for al-Qaida, funding and explosive vests for the Taliban and raised money to support the activities of anti-coalition militants in Afghanistan.
The FBI said Aminullah is believed to be in the Ganj District of Peshawar, Pakistan.