Two persons were shot to death in separate, apparently drug-related incidents about 11 hours apart in an apartment building in Southeast Washington, police reported yesterday. A third shooting in another Southeast apartment house brought the city's homicide total to 26 for 1988.

At 2:25 p.m. Wednesday, Horace L. Pinnock, 34, of the Bronx, N.Y., was shot in a third floor apartment at 625 K St. SE, police said. He died at D.C. General Hospital.

Shortly before 1:30 a.m. yesterday, Larry Darnell Elliott, 31, address unknown, was found in a second-floor apartment with several gunshot wounds, police said. The building is part of the Arthur Capper Dwellings public housing project. Elliott died a short time later.

The city's 26th homicide victim died last night after being shot more than once in an apartment at 828 Barnaby St. SE, police said. The victim, who remained unidentified, was shot about 1:30 p.m. and was pronounced dead about 10 p.m. at Greater Southeast Community Hospital.

Police said the victim jumped out a second floor window in an apparent attempt to escape his assailant. Police have made no arrests in the incident.