Four of the five Americans held hostage in Nigeria by militant groups were finally given their freedom late last night, two days after a promised release failed to materialize. The four men, all employees of Global Industries, a Nigeria-based oil company working for Chevron, were captured three weeks ago in the oil-rich Niger Delta region by a Nigerian militant political group calling itself the Niger Delta Freedom Fighters, also known as "Egbema One." Egbema One released the hostages — Mike Roussel, Chris Gay, Larry Plake and Kevin Faller — to the local governor’s house in Warri, according to media accounts. THE BLOTTER RECOMMENDS Webcast Hostages for Sale? Photos What’s Leading to Terror in the Niger Delta? Blotter Missing: 27 U.S. Citizens; Hopes Dim for Many, Some Held for Years Blotter First Photo of American Hostage From Nigerian Militant Group Click Here to Check Out Brian Ross Slideshows Jack Cloonan, an ABC News consultant formerly with the FBI, is now a hostage negotiator. He says the men are reportedly in good health but will remain in Nigeria for medical check-ups and debriefing before returning to the United States. Another militant group in the region, MEND (Movement for the Emancipation of the Niger Delta), is still holding the fifth American in the region kidnapped last month, oil worker John Stapleton. In an e-mail last week to the Blotter on ABCNews.com, the group’s leader, Jomo, promised that Stapleton, along with five other foreign oil workers from Italy and Croatia, would be released May 30 in order to "spite the outgoing [Nigerian] administration." The country’s government changed hands last Tuesday, May 29. After citing weather and security concerns, Jomo told ABCNews.com in an e-mail today the hostages "will all be released today." Egbema One had demanded more political clout for their tribe and a bigger cut of the region’s oil revenue as conditions for the hostages’ release. It is not known whether those demands were met. Cloonan said Egbema One received pressure to release the hostages from MEND, which is considered a rival militant group in the region.