CHICAGO (CBS) — A reward of up to $25,000 is being offered for information about the armed robbery of a U.S. Postal Service employee Tuesday afternoon in the South Shore neighborhood.

The suspect, armed with a gun, approached the mail carrier outside of the delivery truck in the 7900 block of South Manistee at 12:50 p.m., according to Chicago Police.

The suspect rifled through the mail truck, stole a large quantity of mail and a package, then ran south on Manistee and west through an alley in the 8000 block of South Manistee, according to the U.S. Postal Inspection Service.

The mail carrier was not hurt, police said.

The suspect was described as a black man between 19 and 23 years old, 5-foot-9 to 5-foot-11, 145 to 150 pounds and wearing a black hoodie, a black outer jacket with gray patchwork, a black ski mask and black jeans.

Area South detectives are investigating along with the U.S. Postal Inspection Service, which is offering a reward up to $25,000 for information leading to the arrest and conviction of the robber.

Anyone with information is asked to call Postal Inspector D. Majewski at (312) 983-7879 or U.S. Postal Police at (312) 983-6284. After business hours, tipsters can call (888) 876-5322 or Chicago Police at (312) 747-7581.

(Source: Sun-Times Media Wire © Chicago Sun-Times 2017. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed.)