WOODBRIDGE, Va. — On her first day on the job, Officer Ashley Guindon responded to a call that could have become routine: a domestic disturbance in a well-kept suburban neighborhood.

But one woman had already been slain inside the northern Virginia home of a Pentagon worker, and Guindon would be next. Army Sgt. Ronald Hamilton opened fire as she arrived at his door, killing her and seriously wounding two other officers, police said Sunday.

Prince William County Police Chief Stephan Hudson was glum Sunday as he lauded Guindon’s bravery, intelligence and compassion. The chief offered no details about what might have provoked the gunman, whom the Pentagon was about to transfer to Italy, according to neighbors.

Hamilton, 32, and his wife, Crystal, 29, had been arguing all day Saturday, but it escalated after she called 911, Hudson said. Hamilton fatally shot his wife, fired at the arriving officers and then emerged through his front door to surrender. Officers recovered a handgun and a rifle.

The couple’s 11-year-old son was home at the time of the slayings and is being cared for by relatives, Hudson said.

Guindon, 28, was pronounced dead at the hospital where officers Jesse Hempen, 31, and David McKeown, 33, were being treated Sunday. Police did not detail their injuries. Hudson said they face long recoveries.

Commonwealth’s Attorney Paul Ebert said he would likely seek the death penalty against Hamilton, who was held without bond pending arraignment Monday on charges that included capital murder, first-degree murder and malicious wounding.

Guindon, a former Marine Corps reservist with a master’s degree in forensic science, had been sworn in Friday, which the department marked with a celebratory tweet.

“We were struck by her passion to do this job,” Hudson said. “She couldn’t get it out of her blood. She clearly had a passion to serve others in a way that went beyond herself.”

Guindon’s death was not the first tragedy to strike her family. Her father, David, killed himself the day after he returned home from Iraq, where he served with the New Hampshire Air National Guard. “He came home and took his own life,” Dorothy Guindon, Ashley’s grandmother, told The Associated Press. He was buried with full military honors on Aug. 26, 2004.

Ashley was his only child. She was born in Springfield, Massachusetts, and the family later moved to Merrimack, New Hampshire, her grandmother said. “This is really a shock to us,” Dorothy Guindon said. “Ashley was such a nice person.”

Her line-of-duty death was the fourth in the 46-year history of her department.

Charnita Allen, who lives down the street, said Hamilton’s son was close with her own 10-year-old son and frequently played at their house. Speaking in a soft voice in her driveway Sunday morning, she said Hamilton seemed to be a “nice guy.”

“It’s going to be tough getting over this one,” she said.

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