An airstrike by the U.S.-led coalition fighting Islamic State hit an Iraqi army unit near Fallujah on Friday, killing or injuring 10 Iraqi soldiers, Iraq’s Defense Ministry said.

The ministry said the bombing occurred around noon near the city, which is held by Islamic State, hitting soldiers from the army’s 55th Brigade.

Col. Steve Warren, spokesman for the coalition in Iraq, said the ministry’s report was likely accurate, though he couldn’t provide details on the type of aircraft or munitions involved.

The confusing nature of live combat could have been a contributing factor, he added.

“It was a dynamic strike. It was a troops-in-contact situation,” he said, meaning the U.S. aircraft were likely scrambled to support Iraqi forces who were already engaged in a fight with Islamic State.

A statement later in the day from the coalition said, “despite coordination with the Iraqi security forces on the ground, initial reports indicate the possibility one of the strikes resulted in the death of Iraqi soldiers.” It went on to say this was most likely the first friendly fire incident since the coalition efforts stepped up in mid-2014.

Iraqi army spokesman Brig. Gen. Yahya Rasool said the mistake was announced immediately so as to head off assumptions that it had been intentional.

“We felt that it is very necessary to announce this incident to silence some of the mouths which may talk badly,” he said. “We all know this is a fight and anything could happen in it.”

Two successful coalition strikes against Islamic State then allowed Iraqi forces to make a quick advance on the militant group’s positions in the rural area, it said.

The third strike followed soon after, before the Iraqi troops’ new positions could be relayed to the jet fighters and while weather-induced visibility from the air was poor.

“Our forces suffered casualties,” the statement said.

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