The coalition said the an improvised explosive device's blast occurred in the country's east.
The ISAF previously announced three service members had died.
An individual who opened fire was killed when coalition forces returned fire. The incident is under investigation.
The statement did not provide details about the attack nor the nationality of the service members killed.
NATO usually waits for member nations to provide details about troop deaths.
The year's toll of coalition deaths this year is now 138.