The body of a 17-year-old South Arlington youth was found yesterday at the bottom of an apartment building elevator shaft. County police said he had apparently slipped and fallen seven stories to his death the night before while playing with two friends on top of an elevator.

The identity of the dead youth was not immediately available. Police said he lived in the neighborhood of the building where his body was found, the Park Warren apartments at 5110 S. 8th Rd.

Arlington police spokesman Tom Bell said the two youths who had been playing with the 17-year-old told police they didn't notify authorities of the fall because they were frightened.

"The case is still under investigation, but right now it looks like an accidental death," said Bell.

Police said the three youths were playing atop the elevator about 11:30 Monday night, pressing controls to make it go up and down, when it became stuck at the seventh floor. The 17-year-old fell, police said, when they attempted to climb between the elevator and the shaft wall to reach cables beneath the elevator and climb down the cables.

The body was found shortly before 2 p.m. yesterday by elevator repairmen, police said.