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

But something had already gone terribly wrong inside the northern Virginia home of Army Sgt. Ronald Hamilton, police said Sunday, and Guindon's brief time with the Prince William County police department came to a horrific end. Hamilton opened fire on Guindon and two of her fellow officers, killing her and leaving the others seriously wounded, Police Chief Stephan Hudson said.

Standing next to the county's top elected official and chief prosecutor, Hudson was stone-faced at a news conference on Sunday as he lauded Guindon's bravery, intelligence and compassion. The chief offered no details about what might have provoked the gunman, who worked at the Pentagon and, according to neighbors, was about to be transferred to Italy.

The fight Saturday afternoon between Hamilton, 32, and his wife, Crystal Hamilton, 29, had been ongoing throughout the day, but it escalated after she called 911, Hudson said. Hamilton fatally shot his wife between her call to police and the officer's arrival, and the three officers were shot just after they arrived at his front door, he said.

As quickly as the violence began, it was over, Hudson said, with Hamilton emerging from his front door to surrender as additional officers arrived. 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, died at a hospital, where the two other injured officers — Jesse Hempen, 31, and David McKeown, 33 — were being treated on Sunday. Police did not detail their injuries. Hudson said their lives were no longer in danger but they faced long recoveries.

Guindon was a former Marine Corps reservist and had a master's degree in forensic science, according to Hudson. Guindon served in the Marine Corps Reserves from May 2007 to February 2015 as a field radio operator, said Capt. Andrew Chrestman, a spokesman for U.S. Marine Corps Forces Reserve. She ultimately reached the rank of corporal and was awarded the National Defense Service Medal and the Selected Marine Corps Reserve Medal.

Guindon, a former Marine Corps reservist who had a master's degree in forensic science, went through training with the department last year but left for personal reasons, Hudson said. She rejoined the department this year and was sworn in on Friday, which the department marked with a celebratory tweet.

"We were struck by her passion to do this job," Hudson said. "She did share with us when we rehired her that she felt like she wanted to do this job. She couldn't get it out of her blood. She clearly had a passion to serve others in a way that went beyond herself."

While she was in the Marine Corps Reserve, Guindon graduated from the Embry-Riddle Aeronautical University in Daytona Beach, Florida, with a bachelor's degree in aeronautics and minors in psychology, homeland security and aviation safety, the university announced in a Sunday news release.

"Our hearts are with her family and friends," the news release said.

A Marine Corps official in nearby Quantico, Virginia, offered condolences via Facebook.

Her line-of-duty death was the fourth in the 46-year history of the department, and only the second time a county officer was slain maliciously, county officials said. The county has 446,000 residents, and Woodbridge is one of many bedroom communities popular with federal workers, the military and others who commute to Washington, 30 miles to the north.

"This department is revered. It's respected," said Corey Stewart, the Republican chairman of the county's board of supervisors. "She was an example of the kind of person that the department hires and the quality of the men and women who work for the department."

The county's longtime chief prosecutor, Commonwealth's Attorney Paul Ebert, said he would likely seek the death penalty against Hamilton, who was being held without bond on charges including capital murder, first-degree murder and malicious wounding and was scheduled to be arraigned Monday morning.

Prince William County Police Chief Stephan Hudson, left, accompanied by Prince William County Commonwealth Attorney Paul Ebert speaks during a news conference at the Western District Station, in Manassas, Va., Sunday, Feb. 28, 2016. Ronald Williams Hamilton is being held without bond in the Prince William County Adult Detention Center on charges that include murder of a law enforcement officer Saturday evening. (AP Photo/Jose Luis Magana)
Prince William County Police Chief Stephan Hudson, left, accompanied by Prince William County Commonwealth Attorney Paul Ebert speaks during a news conference at the Western District Station, in Manassas, Va., Sunday, Feb. 28, 2016. Ronald Williams Hamilton is being held without bond in the Prince William County Adult Detention Center on charges that include murder of a law enforcement officer Saturday evening. (AP Photo/Jose Luis Magana)

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 was buried with full military honors on Aug. 26, 2004.

"He came home and took his own life," Dorothy Guindon, Ashley's grandmother, told The Associated Press.

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."

This undated photo provided by the Prince William County Police shows Officer Ashley Guindon. Ronald Williams Hamilton is being held without bond in the Prince William County Adult Detention Center on charges that include murder of a law enforcement officer, Guindon. (Prince William County Police via AP)
This undated photo provided by the Prince William County Police shows Officer Ashley Guindon. Ronald Williams Hamilton is being held without bond in the Prince William County Adult Detention Center on charges that include murder of a law enforcement officer, Guindon. (Prince William County Police via AP)

Mark Doyle, the police chief in Merrimack, told The AP that his officers escorted Guindon's mother and aunt to the airport to fly to Virginia.

"You wonder what she could have been able to accomplish," Doyle said. "We'll never know."

Hamilton's neighbors, too, were struggling to comprehend how a man who had ingratiated himself to the close-knit community in the year since he'd been renting a house there could be accused of such crimes. The neighborhood of $500,000 houses with brick and siding exteriors, manicured lawns and two-car garages is about a 5-minute drive from the county office building.

Charnita Allen, who lives down the street, said Hamilton's son was close with her own 10-year-old son and was frequently over at their house. Speaking in a soft voice as she stood in her driveway Sunday morning, she said Hamilton was a "nice guy" who was visible in the community.

"It's going to be tough getting over this one," she said.

Associated Press writers Matthew Barakat in Woodbridge, Virginia, and Lynn Tuohy in Concord, New Hampshire, contributed to this report. Military Times staff writers Jeff Schogol and Andrew de Grandpre also contributed to this report.