The U.S. Postal Service is offering a $20,000 reward for information that helps catch the man who robbed the post office on 34th Street in Chattanooga this morning.Chattanooga police spokesman Jerri Weary said in a news release that the man came in about 9:30 a.m. and followed a postal worker into her work area where another woman also worked. The man had a gun and made the workers hand over $500 in cash about about $9,000 worth of stamps, the release stated. Then he forced the women to remove their shirts and fondled them before leaving.The robber is black, about 5 feet, 8 inches tall and 150 pounds. He was wearing a hooded black sweatshirt, black toboggan cap and dark pants.The U.S. Postal Service and the FBI are leading the investigation, Weary said.