Two teen-agers and a 28-year-old man were seriously wounded last night in two separate shootings in Southeast Washington, D.C. police said.

The incidents occurred less than 30 minutes apart, but there was no evidence that they were related, according to 7th District police officials.

About 10:30 p.m., a 17-year-old youth was shot near the 2300 block of Hartford Street SE in Garfield Heights. Shortly before 11 p.m., a 16-year-old youth and a 28-year-old man were shot at Wahler Place and Ninth Street SE, near the Washington Highlands public housing complex, officials said.

The three victims, whose names were not disclosed, were taken to Southeast Community Hospital. Hospital officials said the 28-year-old man was in guarded condition with a gunshot wound to the abdomen. The two teen-agers had received mutiple gunshot wounds and were in stable condition, officials said.

The shootings occurred on streets reputed to be busy drug markets. Police said late last night that they were not certain why the shootings occurred, but they said they suspected that drugs were involved.

"Both areas are known to be notorious markets for 'crack,' " a police official said.

Two of the victims were shot near Condon Terrace, a street to which police and residents have referred as one of the District's most volatile open-air markets for "crack" and PCP.