A former Cornell University teacher who recently went to work for the federal government was shot to death and his wife wounded last night by intruders in their home on a quiet street in the Parkfairfax neighborhood of Alexandria.

The man, who had been working for a federal regulatory agency since coming here from Ithaca, N.Y., several months ago, fell in the doorway of his home at 3603 Greenway Place after the shooting, which occurred about 9 p.m., according to neighbors. The woman, shot in the upper part of the body, ran screaming across the cul-de-sac street and pounded on the door of a neighbor for help, according to witnesses.

She was taken to Alexandria Hospital where her condition could not be learned early this morning.

Neither was immediately identified pending notification of relatives. In a brief statement issued last night, Alexandria police said the man and woman were "accosted at their residence" by three assailants, but gave few other details.

Police described the incident as an apparent robbery. It was not immediately known what if anything was taken.

Neighbors interviewed late last night said the couple were in the process of moving from their rented two-story, red brick town house, and said it was believed the intruders might have noticed their door open or ajar.

Neighbors reported that several hours after the shooting police went door to door along the street to ask whether they had seen three men loitering in the neighborhood during the hours from 6 to 9 p.m.

As of early today no arrests had been reported, and the house was cordoned off by police, who said their investigation was continuing.

Although they did not report hearing the gunshots, several Greenway Place residents said they were alerted to the incident by the sound of the wounded woman's screams.

One neighbor said she went out to find the woman bleeding.

"I held her up and tried to talk with her," the neighbor said. "It seemed to me she was fading quickly."

The neighbor asked the woman whether she knew who had shot her.

"There was just no response," the neighbor said.

Instead, the neighbor said, the woman "turned white."

It was "tragic," she said, "sad . . . scary."

The neighbor, along with others interviewed, said there had been few if any reports of violent crime on the short, secluded street, located behind a screen of trees on a landscaped bluff across Shirley highway from the Shirlington shopping center.

Neighbors said they knew few details of the couple's life and had had little close contact with them since they arrived here last summer.

Some said the man took the bus to work to a federal agency job in downtown Washington, but the nature and location of the job were in doubt. Several, however, said they believed he was employed at the Securities and Exchange Commission. Neighbors said the woman was a free-lance writer.

Several neighbors said that the couple had recently purchased a home of their own in the Washington area and had been carrying cartons out of the rented quarters for a day or two in preparation for their move.