U.S. hostage Jeffery Woodke has been released after more than six years in captivity in West Africa, White House national security advisor Jake Sullivan said Monday.

Woodke was kidnapped from his home in Abalak, Niger, where he was a humanitarian aid worker, by men who ambushed and killed his guards, forced Woodke into their truck at gunpoint and drove toward the border with Mali. The incident happened Oct. 14, 2016.

According to Niger's interior minister, Hamadou Souley, Nigerien authorities secured Woodke's release from Jama'at Nusrat al-Islam wal-Muslimin, or JNIM, a terrorist group active in West Africa and the Sahel.

"The U.S. thanks Niger for its help in bringing him home to all who miss & love him," Sullivan wrote in a tweet Monday, referring to Woodke. "I thank so many across our government who've worked tirelessly toward securing his freedom."

Woodke's wife, Els Woodke, told The New York Times that she was notified of his release and told he was in Niger's capital city of Niamey.

A U.S. official confirmed that Woodke was in Niamey and said he was being medically evaluated. Another senior administration official briefing reporters said that the U.S. had not paid a ransom or made other concessions.

Separately, French journalist Olivier Dubois was also released following his kidnapping April 8, 2021 in Mali. Dubois posted a video on Twitter saying he was tired but felt fine.

Media rights group Reporters Without Borders issued a statement Monday, saying it was "overjoyed and hugely relieved" by Dubois' release. The group had long campaigned for his release.

The developments come days after U.S. Secretary of State Antony Blinken visited Niger.

Some information from this report came from The Associated Press and Reuters.

VOA's French to Africa service and Annika Hammerschlag contributed to this report.