A bomb has killed two coalition service members in volatile southern Afghanistan, NATO said.
The statement Monday night did not provide further details or nationalities of those killed.
An Afghan official in Kandahar said there had been a suicide attack on NATO troops Monday evening that also killed civilians. It was not immediately clear if the two incidents were the same. The attacker was on a motorbike, said provincial spokesman Zelmai Ayubi. He did not have casualty figures for either NATO or civilians.
NATO and Afghan troops began a major operation to wrest back control of the south from the Taliban insurgency in July. They have established some pockets of security but insurgents still carry out daily attacks and bombings.
Analysts say the operation's ultimate test of success will be whether it enables the Afghan government to establish its presence and win public support by providing services to the people.
In a separate incident, a remotely piloted aircraft crashed in Behsud district in eastern Nangarhar Province on Tuesday. NATO said it was not carrying any weapons and the crash was not believed to be the result of enemy activity.
Drones are widely used in both Afghanistan and over the border with Pakistan for surveillance and to target insurgent leaders. Some of the strikes have also resulted in civilian casualties.
President Barack Obama has significantly increased the use of the remote-controlled spy planes and recent months have seen a surge of drone attacks aimed at killing Taliban and al-Qaida militants taking shelter in Pakistan.
Associated Press writer Mirwais Khan in Kandahar contributed to this report.