POMPANO BEACH (CBSMiami) – A U.S. Postal Service letter carrier was robbed Monday by a person wearing a mask and brandishing a gun.

The incident happened at 901 NE 12th Avenue in Pompano Beach around 3 p.m.

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The U.S. Postal Inspector Ivan Ramirez told CBS4 the subject stole the carrier’s vehicle keys.

“We do not have any master keys out there floating around.  The keys belong to the vehicle,” Ramirez said.

Broward County Sheriff’s deputies and the U.S. Postal Inspector are investigating.

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The mail carrier got into a short scuffle with the person and had scrapes to his knees according to authorities.

The crime is a federal crime.

Anyone with information should contact the U.S. Postal Inspection Service tip line at 1-888-876-5322.

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A $5,000 reward is being offered for information, arrests and a conviction.