A retired Alexandria couple, their daughter-in-law and three grandchildren were killed in Raleigh, N.C., late Friday night when their car was struck broadside by a tractor-trailer and knocked onto the median strip of a four-lane highway.

William Wallace McMichael, 72, and his wife, Ethelyn Lucille, 69, of 901 Peele Place were killed instantly, police said. Also killed were Celia McMichael, 36, and her three children, Rebecca Colleen, 10, Arron James, 8, and Andrew William, 12. Her husband, William (Mike) McMichael, 35, of Hillsborough, N.C., son of the Alexandria couple, was listed in guarded but stable condition at Rex Hospital.

William and Lucille McMichael had driven to North Carolina last Monday to visit their son, a chemical engineer, and his family, said another son, Ralph McMichael of Springfield. They had planned to return some time this week, in time for a Nov. 6 party celebrating their 50th wedding anniversary. The couple had three children, 10 grandchildren and five great-grandchildren.

North Carolina state police yesterday said the accident occurred at 10:50 p.m. when the McMichaels' car, driven by William senior, pulled in front of a Pine State Creamery truck, apparently in an effort to cross over to an exit off Rte. 70 heading for Durham. The family had been coming from the Raleigh-Durham Airport.

The mother and three children were thrown out of the car, which crashed through the guard rail and landed upright on the median strip, police said. The driver of the truck, who had been traveling at approximately 55 miles per hour, suffered minor injuries.

The survivor in the car, who was conscious after the accident, was on the passenger side of the front seat, State Trooper C.A. Danieley said.

"He was sitting in the right front seat . . . . He asked me, 'Why did I not die too?' I told him that's something I couldn't answer. It was just a miracle," he said.

Neighbors of the Alexandria couple said the McMichaels had lived in their Peele Place house since 1959, and since their retirement had done all the work on the property together. Neighbors said they walked two miles every day, hand in hand.

William McMichael retired from the U.S. Department of Agriculture in 1960, after 35 years. His wife had worked for a life insurance company before she retired, said their son Ralph.