There are new reports tonight that a second American has been killed while fighting with ISIS.

The State Department could not confirm the report, but a senior law enforcement official said authorities are actively investigating reports that a second American was killed this weekend in the same shootout that killed ISIS fighter and California native Douglas Authur McCain.

While some reports suggest that about 140 Americans could be fighting alongside the terror group, other estimates put that number at closer to 300.

9/11 Commission Co-Chair: 'ISIS Snuck Up on Us'

Tonight on “The Kelly File,” Col. Oliver North said that the administration must act – and quickly – on ISIS.

“Doing nothing, or taking too long to act has terrible consequences,” he said.

Watch Catherine Herridge’s report and North’s remarks in the video above.

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