As floodwaters started to recede yesterday, officials in six southern states estimated that at least 28 persons were killed; hundreds of families were left homeless, and several towns were left without food, electricity, roads and telephone service as a result of the heavy rains.

In Southwest Virginia, two persons were reported killed in the severe flooding. In addition, a tornado struck the Eastern Shore town of Onancock, Va., yesterday, toppling a church steeple, uprooting trees and damaging several buildings. No injuries were reported.

Twenty-five primary roads and 130 secondary roads in Southwest Virginia were left impassable, the Virginia Highway Department reported. At least 52 bridges, ranging in length from six to 150 feet were closed and 18 of them were destroyed, a highway spokesman said.

The Virginia Office of Emergency Services reported that 85 patients in the hospital at Grundy in Buchanan County were evacuated yesterday because of the floodwater there. Members of the Virginia Army National Guard and local rescue units transferred the patients to the nearby Richland Hospital.

Late yesterday, emergency phones were being installed in Grundy, which had been without service since late Monday night.

A National Weather Service official said an inch of rain was recorded at Washington National Airport within the last two days. About 2 inches of rainfall were recorded in the western and northern suburbs, he said.

However, local officials said there were no major flooding problems. Today's forecast for the Washington area calls for a high temperature in the low 50s and sunny skies.

Nationally, state rescue officials said the heavy rain and wind storm reportedly killed 18 persons in Alabama, four in Kentucky, and four in West Virginia. In addition, aviation experts suggested that heavy hail or sheet-like rain could have led to Monday's Southern Airways crash near Atlanta, which killed 74 people.

Virginia State Police said one person drowned near Haysi in Dickenson County and a man drowned when his pickup truck went into State Creek at Grundy. Police did not identify either victim.

State officials said there were numerous unconfirmed reports of other missing people, but that it was impossible to determine exactly how many because numerous people fled to homes of nearby relatives and to shelters.

The American Red Cross set up a disaster relief headquarters in Bluefield, Va., to serve the homeless who had to be evacuated from some parts of Southwestern Virginia and nearby West Virginia.

Virginia Gov. Mills E. Godwin, who Monday night delcared a state of emergency in portions of Southwest Virginia, toured the disaster area yesterday. He ordered all state agencies to assit in the emergency.

The state activated 438 members of the Virginia Army National Guard to help in the evacuations.

The National Weather Service said the Eastern Shore tornado, spawned by the rain and thunderstorm activity throughout the South, was reported at 9:03 a.m. in Orancock, which has 1,600 residents.

An Accomack County, sheriff's spokeswoman said the tornado toppled the church steeple into a nearby parking lot and tore part of the church roof. In addition, power lines fell, numerous boats were knocked off trailers and at least five other buildings were damaged, she said.