Prince George's County officials pledged yesterday to hire at least 900 police officers over the next six years in an effort to combat crime as the county's population continues to grow.

"We are committed to this hiring so we have an adequate number of police officers," County Executive Jack B. Johnson (D) said at a news conference. In announcing an anti-crime initiative aimed at posting more officers on the streets during overnight shifts, Johnson vowed to hire 150 police officers in each of the remaining two years of his term and an additional 150 annually in the four years after that if he is reelected.

The police department has about 1,200 officers, with fewer than 500 assigned to street patrols. The county has about 840,000 residents.

Last week, nine people were slain in six days in Prince George's. This year, 98 people have been killed in the county, eight more than the number killed in the same period last year.

"The increase in senseless violence and killings is of great concern to the community and to me personally," Johnson said, adding that a "coordinated and sustained effort" by police, prosecutors and residents will "bring down the homicides."

While other jurisdictions in the region have experienced downward trends in homicides in recent years, Prince George's has not been so fortunate. In 2000, 71 people were slain. In 2002, the number jumped to 137, then fell slightly to 128 last year.

County officials have offered few reasons for the spike in violent crime, but police union leaders and officers have attributed it partly to police staffing.

"As the population grows and the police department doesn't, our officers face a real burden," said Percy Alston, president of the Fraternal Order of Police Lodge 89. "Our calls for service are up to about 2,000 a day. The fact remains that we need a lot more officers to share the workload."

Johnson's promise to hire 150 officers annually "is ideal," Alston said, but may be unrealistic when an average of 10 officers retire from the force every month. Last month, Alston said, 14 people resigned.

"If we hire 150 every year but we lose about 120, then we'll continue to operate at a deficit," he said.

While officials focus on ways to recruit and retain officers, Police Chief Melvin C. High said, the department will continue to make the best use of current personnel. He said that overtime shifts and repositioning of undercover officers will keep neighborhoods covered through the overnight shifts and that tactical teams will continue to focus on areas where homicides and other violent crimes have increased.

"The recent surge in homicides is troubling, and we take the loss of lives very seriously," the chief said. "But the increase in violent crime is a snapshot of a moment in time and, while it is critical, it does not reflect the overall crime patterns in the county. Even with the rash of crimes, we're still optimistic that we'll end the year with fewer homicides than we did last year."

According to department statistics, overall violent crime has fallen by almost 4 percent this year. And total crime in the county, which includes thefts and robberies, has declined by almost 1 percent.

Johnson wants a "coordinated and sustained effort."