The shooting at the Duke Health Center at North Duke Street happened just before 3 p.m. at the corner of N. Duke Street and Frasier Street. That's north of I-85 near the Durham Regional Hospital.
Panicked 911 calls immediately began flooding into emergency operators.
"We're all hiding in a room here," a doctor told a 911 operator.
"The guy with the gun came in and somebody fell through the door," said another caller. "A man came in behind her and shot."
Witnesses reported hearing four shots. They said medical staff were attempting to give the woman CPR, but she was unconscious.
Durham police identified the victim as 49-year-old Charlene Bullock King. Relatives told ABC11 that she worked at the center for 27 years as a phlebotomist. They said the gunman was her ex-boyfriend.
Police identified him as 52-year-old Burnette Taylor of Durham.
"Charlene was very sweet, very sweet," King's stepson Steven Shealey said. "She didn't deserve this at all. Even at one point when I was going through some things with my fiancé, she took me in."
He said she had recently had a fight with Taylor and decided to leave the relationship.
"I guess he realized he had lost something that was a jewel, something that was precious as she was, and that's why he couldn't let go," Shealey said.
After the shooting, Durham police quickly swarmed the area trying to find Taylor who took off on foot.
"We happened to have officers training not too far from here at that point in time, so they were able to respond at a very quick rate," Durham Police Chief Jose Lopez said.
Witnesses reported the gunman ran into a wooded area behind a house on Carver Street. They reported hearing multiple gunshots before Taylor was seen lying on the ground.
As police tracked Taylor, Lopez said he "engaged police officers in a gun battle" at Carver and Broad streets.
Taylor was shot by officers and Lopez said he was taken to Duke Hospital where he later died.
Lopez said the North Carolina State Bureau of Investigation would be assisting in the case - as is standard in any officer involved shooting.
Taylor had a long criminal record. According to the North Carolina Department of Corrections, he was a registered sex offender after convictions for second-degree rape and kidnapping in 1993. He also has convictions for car theft, larceny of firearms, resisting arrest, and drunk driving.
After serving time for those crimes, he was released and apparently began dating another woman, who late-last year accused him of assault. The woman even requested a temporary restraining order, describing a violent episode in which Taylor beat her unconscious. In court documents she wrote, "He continued to slap, kick, punch me with his fists. Blackening both my eyes, fracturing my ribs, my liver was cut due to a kick."
Probation officers put out warrants for Taylor's arrest beginning in November of last year.
State correction officials say Taylor's probation officer made every attempt to locate him, but officers never managed to track Taylor down, until six months later when Durham police officers shot him Tuesday.
Officials with the North Carolina Department of Correction also say their revue shows the probation officer made numerous attempts to find Taylor over the last six months, at his last known address and his family members, but Taylor was willfully fleeing supervision.
Meanwhile, Duke Medicine reopened on Thursday after it cancelled all appointments for all services at the Duke Health Center at North Duke Street for Wednesday.
Patients with questions about their appointments can call (919) 613-7650.