WASHINGTON — Americans have been killed by prisoners released from the detention center at Guantanamo Bay in Cuba, a senior Defense Department official told lawmakers Wednesday, triggering sharp criticism from Republicans opposed to shuttering the facility.

Paul Lewis, Pentagon special envoy for Guantanamo closure, declined to provide the GOP-led House Foreign Affairs Committee with details. He would not say if the episodes occurred before or after President Obama took office in 2009. ‘‘What I can tell you is unfortunately there have been Americans that have died because of [Guantanamo] detainees,’’ Lewis said during an exchange with Representative Dana Rohrabacher, Republican of California. ‘‘When anybody dies, it is tragedy and we don’t want anybody to die because we transfer detainees.’’

An administration official said Lewis was referring to a case that involved an Afghan released while George W. Bush was president.

During the Bush administration, 532 prisoners were released from Guantanamo, often in large groups to Afghanistan and Saudi Arabia.

The Obama administration has released 144 detainees after a screening process that involves six agencies and departments that must make a unanimous decision to release.

Lewis testified along with Lee Wolosky, the State Department’s special envoy for Guantanamo. They argued the prison is a powerful propaganda tool for the Islamic State group and keeping it open damages US national security.

Republicans and a few Democrats have thwarted Obama’s effort to close the prison and blocked any attempt to move detainees to US prisons.

Wolosky said Guantanamo did not prevent Tuesday’s attacks in Brussels, or the Nov. 13 attacks in Paris. ‘‘There are unfortunately going to be acts of terrorism, probably whether the facility is opened or closed,’’ he said. The director of national intelligence reported that 5 percent of Guantanamo prisoners released since January 2009, when the multiagency screening began, have reengaged in terrorism; 8 percent are suspected of it.