WASHINGTON (AP) — An American aid worker who was kidnapped in the West African nation of Niger more than six years ago has been released from custody, the Biden administration said Monday.

Jeffrey Woodke was kidnapped from his home in Abalak, Niger, in October 2016 by men who ambushed and killed his guards and forced him at gunpoint into their truck, where he was driven north toward Mali’s border.

A senior administration official who briefed reporters Monday on Woodke’s release described the action as the culmination of years of efforts, but declined to say what exactly led to him being freed from captivity or where he is now.

The official said no ransom was paid and no concession was made to captors.