Jefferson County Sheriff Fred Abdalla needs no reminder that he or any one of his deputies could be killed at any moment in the line of duty.

Penn Hills, Pa., police officer Michael Crawshaw, 32, was killed Sunday evening when an assailant approached his cruiser, opened fire with what appeared to be an assault rifle and fled, Chief Howard Burton said. Police searched for the suspect and would not say Monday morning whether anyone was in custody.

Abdalla called Crawshaw's death a "heartbreak." However, he said the officer's murder did not serve as an eye opener to the dangers of his job.

"An officer doesn't have to be shot and killed for another officer to be reminded that it is dangerous - he knows when he walks out the door," Abdalla said. "I think of it often. Today, you don't know. Any time (an officer) could be killed by an idiot. I pray every day about keeping my family safe and then my officers safe."

Crawshaw was pronounced dead at University of Pittsburgh Medical Center Presbyterian Hospital shortly before 9 p.m. Sunday. He was shot as he sat in the cruiser, parked two doors down from where officers responded to a 911 call. The car was shot several times, including twice through the windshield.

The slain officer is the fourth to be killed on duty in Allegheny County this year. Pittsburgh Officers Eric Kelly, Stephen Mayhle and Paul Sciullo were shot in a gun battle while responding to a call at a home in April.

Abdalla said all of those deaths are troubling, particularly that of Crawshaw.

"He shot him while he was sitting in the car - what a coward," Abdalla said of the shooter. "I don't know if he has family and kids or what, but what a heartbreak. ... Four officers killed in a year - it's all heartbreaking."

According to reports, all four of those officers were killed while responding to reports of domestic violence. And no one knows better than Wheeling Police Chief Robert Matheny the dangers involved in responding to reports of violence in the home.

In 1992, Matheny was stabbed in the chest while investigating a domestic call. He said his protective vest saved his life, as he suffered only minor injuries. Matheny was attacked by a man wielding an 8-inch butcher knife. The chief said the blade was left bent at a 45-degree angle as a result of the attack.

During that same incident, the man who attacked Matheny also managed to pull the firearm from the holster of another officer. He fired one round, but no one was shot.

Matheny said the subject of that investigation spent 10 years behind bars because of his actions.

Matheny said that instance, and those in which the four Pennsylvania officers were killed, clearly demonstrate the dangers officers face in situations of domestic violence.

"Emotions are at their highest," Matheny said in explaining why domestic violence situations are so dangerous. "You have to have a certain amount of readiness."

Matheny said Crawshaw's death is troubling, and the possibility of a Wheeling officer being shot and killed is something he fears.

"It scares the hell out of you," Matheny said. "As a chief, it scares me for the men and women here at work."