(KABUL, Afghanistan) -- Monday turned out to be the deadliest day of the year for U.S. forces in Afghanistan as officials said that a helicopter crash outside of Kandahar killed five Americans on board.

NATO claimed the Black Hawk went down in an area where there was no enemy activity reported.

It was the deadliest aircraft crash involving U.S. forces since last August when seven Americans died after their helicopter was hit during a firefight with militants.

Earlier Monday, two U.S. Special Forces members were gunned down in an "insider attack" in Wardak province, bringing the day's death toll to seven.

The fatalities occurred after more than a month of no U.S. casualties in Afghanistan.

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