Police in Santa Rosa who fatally shot a domestic violence suspect Wednesday night allege he approached them with a gun in his hand, the department said Thursday. 

On Wednesday at about 10:12 p.m., officers responded to a residence in the 900 block of Keegan Drive in Santa Rosa. Police were told a man was armed with a gun and had allegedly committed domestic violence against his ex-girlfriend and the mother of his child, the department said.

As officers arrived, three adults and an infant had safely left the residence. One woman, a 19-year-old mother of a two-month-old baby, had allegedly been pistol-whipped in the head by the suspect.

The suspect, a 20-year-old Santa Rosa resident, barricaded himself inside the home and allegedly refused instructions to peacefully surrender, according to police.

A SWAT and negotiations team arrived at the scene at about midnight and attempted to get the suspect to surrender peacefully. At 4:55 a.m., the suspect allegedly ran out of the house with a firearm in his hand in the direction of officers.

"Initial reports indicate that one SRPD SWAT officer fired at least one round at the suspect," said Santa Rosa police in a statement released Thursday. "Officers immediately began providing medical aid to the suspect, who had sustained at least one gunshot wound."

By 4:57 a.m., the suspect was declared deceased. Police have not released the names of the officers involved or the suspect.

Since this was an officer-involved shooting, both the Sonoma County Sheriff's and District Attorney's offices will lead independent investigations into the shooting.