A 25-year-old Yakima woman was arrested after Yakima police say she strangled her 4-year-old stepson to death Wednesday night.

Yakima Valley Memorial Hospital received a call from 911 around 11:03 p.m. that an unresponsive child was coming to the hospital in a private car, YPD Capt. Jay Seely said. When the woman and the child arrived, the boy had no pulse and wasn’t breathing, Seely said, and he was pronounced dead after hospital staff performed CPR for 30 minutes.

Hospital staff called police based on the circumstances and the woman’s statements, Seely said. A police officer noticed bruising on the boy’s body and YPD’s Special Assault Unit detectives went to the hospital, Seely said.

Detectives questioned the woman and obtained evidence that the boy had been strangled, and arrested the stepmother, Seely said, State Child Protective Services have taken two other children at the home in the 1100 block of McKinley Avenue into protective custody, Seely said.

She was booked into the Yakima County jail Thursday morning on suspicion of second-degree murder. The boy’s father, who was at work, is not a suspect, Seely said.

“This is such a tragic end to this young child’s life,” Seely said. “I want to commend the Memorial Hospital staff for their work, and the special assault detectives who worked through the night to investigate this case.”

Chief Yakima County Deputy Coroner Marshall Slight said the boy will be taken to Seattle Friday for an autopsy at the King County Medical Examiner’s Office.

The boy’s death is the second homicide in the county and the city this year, and the second homicide this week. Clayton Peter Brown Jr., 38, was found dead with a gunshot wound to the head at the Yakima Inn Tuesday night.

Reach Donald W. Meyers at dmeyers@yakimaherald.com or on Twitter: donaldwmeyers, or https://www.facebook.com/donaldwmeyersjournalist.