The victim, Arthur Edward King, 22, told police he was walking in an alley east of South Potomac Street at 12:11 a.m. when he was attacked by three or four men.
King said he was ordered to his knees at gunpoint and told to give up his money. When he said he didn't have any, the men took his wallet and began to beat him, police said.
One of the robbers hit King in the head with a bottle, causing a large cut on the top of his nose which bled profusely.
The robbers fled when a truck drove into the alley, police said. King was treated at Washington County Hospital.
Green and Pfeltz have charged with armed robbery, robbery, accessory to robbery, first- and second-degree assault, and reckless endangerment.
The 15-year-old is charged as a juvenile with accessory to robbery and second-degree assault. He was being detained at the Juvenile Holdover Facility on Jonathan Street.
Pfeltz is being held in the Washington County Detention Center on $15,000 bond.
Already implicated in an unrelated Jan. 13 armed robbery, Green was charged with that crime last week and was being held on $30,000 bond.
The incident on Jan. 13 occurred at 1:45 a.m. at the intersection of East Franklin and Mulberry streets when two men "helped" Robert West push his disabled vehicle, according to Washington County District Court records.
West, 37, address unknown, pulled out his wallet to pay the two men for their kindness when they allegedly grabbed his money and told him they had guns.
Green was charged with attempted armed robbery, first- and second-degree assault and misdemeanor theft in that case, Knight said.
A second man was still being sought, police said Tuesday.