Kabul, Afghanistan (CNN) -- Six members of NATO-led forces in Afghanistan were killed Monday in three separate incidents, NATO announced.

It was the deadliest one-day total since October. On two consecutive days -- the 26th and 27th -- seven members of the NATO-led International Security Assistance Force were killed.

On Monday, three U.S. service members died during a firefight with militants in southern Afghanistan, NATO officials said.

In eastern Afghanistan, two members of the NATO-led forces were killed in an engagement with enemy forces.

Although NATO did not supply the nationalities of the two fallen combatants, the French Ministry of Defense announced that one of its soldiers was killed in a gunbattle in the village of Alasay, which is in eastern Afghanistan.

Another soldier was killed by an improvised explosive device in eastern Afghanistan, the ISAF reported. No nationality was given for that soldier either.

NATO did not offer additional details.