KABUL, Afghanistan (CNN) -- Four American troops were killed Thursday in western Afghanistan when their vehicle hit an improvised explosive device, NATO's International Security Assistance Force said.
ISAF said U.S. spokesman Chief Petty Officer Brian Naranjo confirmed the service members were from the United States.
No further details were released.
Earlier Thursday, ISAF said a U.S. service member had died Wednesday in western Afghanistan after NATO troops engaged insurgents who were spotted planting roadside bombs.
The NATO troops were able to thwart the insurgents, but shortly afterward their patrol struck a hidden bomb, killing the American, ISAF said.
The name of the service member is being withheld until next of kin have been notified.
The August U.S. death toll in Afghanistan stands at 11.