(CNN) Vice President Mike Pence's press secretary was impersonated in fraudulent text messages sent to some Republican members of Congress seeking their whereabouts, a source familiar confirms to CNN.

The FBI is investigating the matter, the source confirmed.

The Wall Street Journal previously reported on the text messages.

Republican Rep. Adam Kinzinger of Illinois was among those contacted by someone impersonating White House staff, according to his spokeswoman Maura Gillespie.

"For months, we have referred these hoaxes to law enforcement, but only recently has there been a renewed interest to address the issue," Gillespie told CNN in a statement. "Congressman Kinzinger is eager to cooperate with law enforcement as they see fit."

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