NATO did not provide any further details in its Sunday statement. It says the attack occurred on Saturday.
Their deaths bring October's toll of foreign troops killed to six, with a total of 460 deaths so far this year.
Afghan police say eight insurgents and a police officer have been killed in a separate incident in southwestern Nimroz province. Nimroz provincial police chief Gen. Abdul Jabar Perdali said the gunbattle took place Saturday, and that it lasted five hours.