A veteran Baltimore police officer has been charged with first-degree murder, accused of shooting a woman and then barricading himself inside a home with a 4-year-old boy believed to be his son. (WJZ video)

Two Baltimore police officers arrived at a fellow officer's home to investigate a reported domestic assault. They heard a woman inside calling for help, and when nobody answered the door, they kicked the door in and brought Kendra Diggs out.

James Smith, 49, ran upstairs as an officer implored him to come and talk. The other officer stood on the sidewalk next to Diggs, her face bleeding from a small wound. A shot rang out from a second-story window, authorities say. Diggs, shot in the head, hit the ground, and Smith and his fellow officers commenced a six-hour standoff.

Details of the shooting and standoff this week emerged in a court hearing and charging documents Wednesday, the day after Smith is alleged to have killed his girlfriend and then barricaded himself in the West Baltimore home with a toddler who family members said was the couple's son.

Smith, an Army veteran and a skilled, highly respected police officer, released the boy and surrendered peacefully late Tuesday. Charged with first-degree murder and use of a handgun in a felony, he is being held without bail.

No lawyer is listed in court records for Smith. In court on Wednesday, a pretrial services official said Diggs, 37, and Smith, 49, had lived together in her house in the Sandtown-Winchester neighborhood for eight years. Diggs' aunt, cousin and neighbors said the two were engaged and planned to marry soon in the Bahamas.

Diggs left two children, Brandon, 20, and James Jr., 4. She had the younger boy with Smith, her cousin Sharifah Ahmed said. James Jr. was allowed to see family members Tuesday night but was placed in foster care overnight. Ahmed said Brandon is seeking custody of his younger brother.

Diggs worked as a Maryland Transit Administration bus driver for 13 years, an MTA official said. She was wearing her work uniform when the two Western District officers responded to the domestic call Tuesday, according to charging documents.

When the officers arrived at the brick townhouse in the 1100 block of N. Parrish St., police say, they heard a woman yelling, "Help me, help me."

A man shouted, "Go away."

After the officers escorted Diggs outside, police say, they saw Smith run upstairs, refusing to come down to talk.

Diggs had warned the officers he had a gun, police say. When the gunshot rang out, they fled for cover.

Under the threat of more gunfire, emergency workers were unable to reach Diggs, who remained on the sidewalk. After about an hour, tactical officers were able to pick her up and take her to an ambulance. She was pronounced dead at Maryland Shock Trauma Center.

On Wednesday, Diggs' aunt and cousin drove to her home carrying a teddy bear decorated with balloons that said "You're so special" and "You'll be missed." They placed the toy at the edge of her front lawn, inches from a bloodstain where Diggs had fallen.

Ahmed, her cousin, shook her head Wednesday as she stared at the immaculately manicured property — Diggs' pride and joy.

"She was an extremely happy, happy person," Ahmed said. "It was her first home she had ever bought, so she was just in love with it."

Fresh mulch surrounded green shrubs, flowers bloomed in a planter hung near the door and dragonfly and butterfly ornaments were affixed to the walls. The only glaring imperfection was the broken second-floor window, which revealed a ceiling fan light still burning inside.

Ahmed said family members are struggling with Diggs' loss — especially because they believe the officers should have taken her farther away from the home.

"The Police Department has a lot to answer for," Ahmed said. "When they got on the scene, why didn't they remove her immediately? … She was yelling for help."

Ahmed said she believes officers gave Smith the benefit of the doubt that he wouldn't do anything rash "because he was a police officer."

Baltimore police spokesman Anthony Guglielmi stressed that the initial response to the house is under internal investigation, as is the entire standoff.