A 26-year-old pregnant woman was killed after she was stabbed by an attacker and hit by gunshot fired by police, Fayetteville authorities said Monday.

Police have arrested Jill Ulmer's ex-boyfriend, Ricky Ray Anderson, on suspicion of second-degree murder. According to authorities, Ulmer had a restraining order against Anderson and called police Friday night because Anderson had been calling her and sending text messages.

When officers arrived at Ulmer's Fayetteville apartment, they heard Ulmer screaming, authorities said. Fayetteville police say two officers fired several rounds through a window at Ulmer's attacker before entering her Fayetteville apartment. One round struck Ulmer, who was on the floor bleeding from multiple stab wounds, police said.

Anderson was arrested in Ulmer's apartment, police said. Police also recovered a bloody knife from the apartment, Cpl. Craig Stout said.

The state medical examiner's office said Ulmer would have died from either the stabbing or the gunshot. The examiner's report, released Monday, also confirmed that Ulmer was pregnant.

Police say the officers involved have been placed on paid leave, pending an internal investigation.

"The Fayetteville Police Department is saddened by the tragic death of Ms. Ulmer," police Chief Greg Tabor said in a statement Monday. "It is unfortunate our efforts to prevent her murder were unsuccessful."

Anderson is on parole for aggravated assault and robbery in Oklahoma, The Morning News reported. He remains in the Washington County jail without bond. It wasn't clear Monday night whether he had an attorney. He has a preliminary hearing set for July 27.