A suspect in the robbery of a bank in the Waterside Mall was shot and killed there yesterday by an off-duty D.C. policeman as the youth reached for a gun.

Police said Ernest Moss Jr., 16, of 4321 Ninth St. SE, was pronounced dead at George Washington University Hospital about an hour after the 9:55 a.m. shooting.

The officer, Elton L. Pinkard, a 10-year veteran of the police department, has been placed on administrative leave pending an investigation of the incident at the National Bank of Washington's branch at 401 M St. SW, police said.

Pinkard is an investigator in the recruiting branch of the department's personnel division.

Police said a youth entered the bank branch about 9:55 a.m., approached a teller, gave her a brown paper bag and told her to fill it with money. He indicated he had a gun, police said.

Pinkard, who was in the bank on private business, was told by another teller that a youth who was leaving the bank appeared to be the same person who had held up the branch on Jan. 20, police said.

Homicide detectives said Pinkard approached the youth, identified himself as a police officer and ordered the youth to halt. The youth turned around and appeared to reach for a gun in his belt, police said. Pinkard drew his service revolver and fired one shot, striking the youth in the chest.

The youth collapsed at the bank's front door. He was pronounced dead at George Washington University Hospital about an hour later. Police said a brown bag filled with money and a .25-caliber automatic handgun were found near the front door of the bank.