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.

READ MORE: Florida's Nikki Fried Weighs Action Over DeSantis' Environmental Appointment

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.

READ MORE: Florida Judge Blocks Key Parts of 'Sanctuary Cities' Law

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.

MORE NEWS: Gabby Petito's Cause Of Death Pending As Brian Laundrie Still Nowhere To Be Found

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