(CNN) Investigators believe San Bernardino shooter Syed Rizwan Farook may have been plotting an earlier attack in California with someone else, two U.S. officials said.

One of the officials said the two conspired in 2012 and a specific target was considered. Neither of the officials could say how serious the plotting got.

One official said the two decided not to go through with the earlier attack after a round of terror-related arrests in the area.

"They got spooked," the official said.

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