Officials said the suspect walked into "Ken Marble Inc." on Flushing Avenue in Clinton Hill through an open door around 5:45 p.m.
Dramatic surveillance video shows the suspect enter the office and point a gun at the 53-year-old victim. The video shows him pointing the gun in several directions.
Police said the suspect demanded money from the woman and stole her pocketbook, which contained an iPhone 5 and $800 cash. He then fled the scene.
No injuries were reported.
Police described the suspect as a 25-year-old black man with a medium complexion who weighs approximately 200 and is six feet tall. He was last seen wearing a black knit cap, a black waist-length jacket, black faded jeans, black sneakers and a multi-colored scarf.
The NYPD is offering up to $2,500 for information regarding this case.
Anyone with information in regards to the above incident is asked to call Crime Stoppers at 1-800-577-TIPS (8477). The public can also submit tips by logging onto the Crime Stoppers website at WWW.NYPDCRIMESTOPPERS.COM or by texting their tips to 274637 (CRIMES) then enter TIP577.
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