Federall investigators studying contacts suspects had in the U.S. and abroad.

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WASHINGTON, D.C. (CBSDFW.COM/AP) — On the same day the Islamic State claimed responsibility for the attack outside a Muhammad Art Exhibit in Garland Sunday night, the White House said Tuesday “it’s too early” to be confirmed. White House spokesman Josh Earnest said that the ISIS group and others were trying to capitalize on social media to radicalize people in the U.S.

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An ISIS bulletin was announced on Al Bayan Radio calling the suspects “soldiers of the Caliphate.”

In March, CBS 11 reported on a handful of law enforcement agencies that had been alerted by the federal government that some North Texans are on an ISIS hit list.

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The Department of Homeland Security and the FBI issued a joint intelligence bulletin to local law enforcement on April 20 warning that the Garland event was a possible target for a terrorist attack, according to a DHS official who was not authorized to be quoted discussing the document.

Earnest says U.S. officials are aggressively working to counter terrorist efforts on the web and social media.

When asked if the Islamic State group has now come to the U.S., Earnest said: “We would certainly want to make sure that we know a whole lot more about the facts” before drawing such a conclusion.

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