A District police officer shot and killed a 63-year-old Northwest Washington woman who had stabbed a man with a kitchen knife yesterday and was trying to stab him again, D.C. police said.

Officer Christopher Hester, 27, shot the woman in the doorway of an apartment at 1630 Park Rd. NW, after she pulled the knife out of the victim's back, prepared to plunge it in again, and refused to obey the officer's order to drop the weapon, police said.

The officer, accompanied by another officer and a police official, was answering a call for a domestic quarrel at the apartment about 1 a.m. They were met at the door by Ottis Lee Herndon, 35, who spoke in an unintelligible manner, police said.

The woman, whose name has not been released, came up behind Herndon and suddenly stabbed him, police said.

The woman died about 2:30 a.m. at the MedStar unit of the Washington Hospital Center.

Herndon was listed in fair condition at the Hospital Center with a stab wound in his left shoulder, said hospital spokeswoman Mary Anderson.

The officer was placed on routine administrative leave with pay after the incident, police said.

The Park Road incident was the city's fourth homicide since Tuesday, bringing the total for the year to 51, which is 18 more than this time last year.

Police said that Keith Mark Jackson, 21, of 346 Raleigh St. SE was shot several times Tuesday in front of 3537 11th St. NW and died yesterday at the Washington Hospital Center.

Andrew Lewis Green, 23, of 1224 I St. NE died Wednesday at D.C. General Hospital of stab wounds he received following an argument earlier in the day outside of 1216 I St. SE, according to police.

Theodore J. Scott, 28, of 1810 I St. NE died Wednesday at D.C. General about 8 p.m. after an altercation that evening in which he was stabbed in the chest outside 1814 I St. NE.