An off-duty District police officer was shot in the shoulder yesterday in an incident in Charles County that has police officials there puzzled.

Late yesterday, police said the events that led up to the shooting of 1st District officer Yolanda Davis Saucedo were as yet "undetermined."

They would not say whether the wound was self-inflicted or was caused by Saucedo's service revolver, or whether someone else was involved.

Saucedo underwent surgery at the Prince George's Hospital Center, and police said that she was in stable condition.

Charles County police were called to a house on Bryans Road in the Marshall Hall Park area around 3:50 a.m., police said.

Saucedo, who joined the District force in 1986 and lives in the District, was taken by Maryland State Police helicopter to the hospital.

There were conflicting reports from police agencies about where Saucedo, 30, was found after the shooting.

Charles County authorities said she was found wounded in the residence, but a spokesman for the District reported she was found in a car outside the house.

Charles County police are handling the investigation. They declined to give the exact location of the Bryans Road house.

Officials from the District and Charles County questioned Saucedo at the hospital yesterday morning but would not comment on the information she gave.

"What it boils down to is this: I'm not sure of the details," Charles County Detective Michael Wyant said. "In all fairness, that is all anybody is going to say."

Charles County officials said more details would be released today after interviews with witnesses and further investigation. Staff writer Joseph E. Bouchard contributed to this report.