An Anne Arundel County police officer yesterday shot and killed an 18-year-old man who, according to police, reported a burglary at his Severna Park house and then, using a butcher knife, attacked the officer who responded to the call.

Douglas James Ashby of 103 Bellehahn Ct. was pronounced dead shortly after 2 a.m. at Anne Arundel General Hospital, said Richard Molloy, a spokesman for the Anne Arundel County police. Ashby had been shot in the throat and chest, Molloy said.

Ashby called county police about 12:50 a.m. to report a break-in at his house, where he lived with his parents, an older brother and a younger sister, according to Molloy.

Officer Charles S. Brown, a five-year veteran on the force, responded to the call five minutes later, Molloy said.

"The door was opened immediately when officer Brown knocked," Molloy said, and Ashby said, 'You're here.' "

When Brown stepped inside the house, Molloy said, Ashby threatened him and swung the knife toward the officer's head, cutting him across his throat.

Ashby repeated his threat twice more and again came at Brown with the knife, Molloy said. Brown shoved Ashby away, according to Molloy, drew his revolver and then fired two shots at Ashby.

Brown, who administered CPR to Ashby until paramedics arrived, was treated for the cut across his throat at North Arundel Hospital and released.

Brown was placed on administrative duty pending the outcome of investigations by the department's homicide and internal affairs sections.

Police, neighbors and relatives yesterday said they were puzzled by the incident.

Ashby had hosted a party at the house on Saturday night, police said, and he became angry when his girlfriend showed up with a date.

The party had ended a short time before Ashby called police, Molloy said. "Why he called in a breaking and entering and why he attacked officer Brown, we don't know," Molloy said.

"There was nothing to indicate that there had been a break-in or that Ashby believed officer Brown was an intruder," Molloy said.

Autopsy results are expected today, Molloy said.

Neighbors said they did not hear any loud noises coming from the Ashbys' house Saturday night and said they were surprised by the police version of the incident.

The neighbors described Ashby, who was a freshman business major at Loyola College in Baltimore, as a polite and well-mannered person.

"He was a pleasant kid, always said hello . . . didn't disrupt the neighborhood," said Ted Tussing, who lives on Old County Road across from the Ashbys.

Ashby's parents were out of town yesterday. Bruce Ashby, Douglas Ashby's older brother, said he could not figure out what happened.

"The details are still shaky," Bruce Ashby said. "All I know is what police told me. It's so out of character. It's tragic."