A 16-year-old youth, apparently working as a roofer, was fatally injured in a seven-story fall to the asphalt in an alley near 11th and F Streets NW yesterday afternoon D.C. police reported.

Police identified the youth as John Johnson, but his address was not immediately known.

Police said Johnson's fall was broken only when he bounced off the overhanging roof of an adjacent building about five feet below where his fall began. They said the incident was reported at 4:28 p.m.

Johnson was pronounced dead at Washington Hospital Center at 6:43 p.m., police said. The fall occured from a building at 1111 F St. NW, they said.

Detective Raymond J. Green said police believe Johnson was clipped on the side by a wooden scaffolding as it was being moved into position. Green said the youth's two partners said he was standing on an outside landing between the sixth and seventh floors of the building whe n the accident occured.

Green said Johnson's two coworkers said he fell the five feet to a nearby roof before he "bounced" and fell from the roof into a small gap between the buildings.

The dectective said the three workers were doing renovation work on the 10-story building.

Doctors at the Hospital Center said last night before Johnson died that he suffered severe and multiple internal injuries.