(CNN) -- The governor of Afghanistan's Kunar province said Sunday that 64 people, including some civilians, were killed in a joint operation by NATO's International Security Assistance Force and Afghan security forces over the past few days.

Sayed Fazlullah Wahidi told CNN that the dead included 16 insurgents, 22 women, and 26 young boys.

ISAF said its reporting and weapons system video showed that 36 insurgents carrying weapons were killed.

"We take allegations of civilian casualties very seriously. We are conducting an immediate assessment of these allegations and will report our findings," U.S. Army Col. Patrick Hynes, director of ISAF's Joint Command Combined Joint Operations Center, said in a statement.

ISAF said it is sending an incident assessment team to look into the allegations.

The operation took place "in a very remote valley in Kunar province, over very rugged terrain in the late night/early morning hours," ISAF said in the statement.

Wahidi, the governor, said the operation "started three days ago in Azgal valley of Ghaziabad district," which he described as under government control but remote.