It added "the peace and stability of our beloved nation as regards to protection of the lives, liberty and property of individuals must at all cost be preserved and jealously guarded."
Eight men and one woman were removed from their prison cells Friday night and executed, London-based Amnesty reported, quoting "credible sources." It said two of those executed are believed to be foreigners from Senegal.
A barrage of protests met the move, with expressions of shock coming from the African Union, the Economic Community of West African States, the French and Nigerian governments and human rights groups.
It was not clear how the prisoners were executed, but Gambia's constitution says executions should be by hanging. "What is however clear is that inmates were rounded up at 9.30 p.m. Thursday August 23 and that by the morning of August 24, the bodies were actually lying in the Mile Two Prison yard," the Civil Society Associations of Gambia reported.
Amnesty warned "more persons are under threat of imminent executions today and in the coming days."
Amnesty said the executions are the first in Gambia since 1987. Gambia reinstated the death penalty in 1995 but had not executed anyone, former minister Omar Jallow has told The Associated Press.
Amnesty said there were 47 inmates on death row before Friday's executions: government figures put the number at 42 men and two women and another three men reportedly also received the death sentence this year.
Capital punishment can be imposed in Gambia for murder and treason. Three of those reportedly executed had been sentenced for treason, Amnesty said. It's not known how many of those on death row have been sentenced for alleged coup-plotting, a treasonable offense that could indicate Jammeh is using the executions to get rid of political opponents.
Jammeh was reelected in November in elections that were "neither free nor fair," according to the U.S. State Department. Its annual human rights report criticized "the government's harassment and abuse of its critics, which resulted in a muzzled press and the death, torture, arrest and detention, and sometimes enforced disappearance of citizens."
Amnesty called the executions, if confirmed, "a hugely retrograde step" putting Gambia among a minority of African states that still impose the death penalty. Thirty-eight of the 54 members of the African Union have abolished the death penalty or, if it is still in their law books, do not perform executions, Amnesty International said.