KNOXVILLE, Tennessee (AP) — Police say a gunman who opened fire outside a Tennessee hospital was mentally ill and thought a monitoring device had been implanted in him during an appendectomy in 2001.

Knoxville Police Chief Sterling Owen IV identified the gunman as Abdo Ibssa, a naturalized citizen from Ethiopia. The gunman shot three hospital workers, killing one, before killing himself.

Owen said Ibssa first entered a medical tower near Parkwest Medical Center and asked for the doctor who performed the appendectomy. He then went to another area where patients are discharged and opened fire.

Owen said a note alleging the doctor implanted a chip was found in Ibssa’s apartment after the attack. Owen said Ibssa’s family had him committed for mental treatment in February.

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KNOXVILLE(AP) — A gunman who opened fire outside a Tennessee hospital seemed focused on the sprawling medical complex, directing his cab to stop first at an adjacent tower before he went to another entrance where he killed one medical worker and wounded two others, a taxi driver said.

Police haven’t said whether the gunman had a connection to the Parkwest Medical Center, where he shot the three women before killing himself. The women were current or former workers at the hospital, police said.

Cab driver Freddys Sakhleh said he picked up the gunman outside an apartment complex, and the man told him he wanted to go to the western side of Knoxville. They stopped at an ATM, where the suspect withdrew $20 before telling Sakhleh to take him to the medical center complex.

Sakhleh said the man seemed angry and depressed and said little about himself, only that he was from Atlanta.

Police, who planned an afternoon news conference, haven’t yet released the gunman’s name or any motive for the attack.

Sakhleh said he was directed to take the man to the medical center tower and told to wait for him to come back. When his passenger returned, Sakhleh said, he told the driver to take him to the hospital entrance.

Sakhleh said the man then got out of the cab, handed him $20 and told him to wait five minutes. He returned, grabbed a gun from his waist and started shooting, first to the right and then to the left.

“I called 911, and I said, ‘Please send some people here, this man is shooting like crazy,'” Sakhleh said. He said the gunman then shot himself in the head.

“All of this happened in a matter of seconds,” the driver said.

The shooting happened Monday outside the discharge area at Parkwest Medical Center, Knoxville Police Chief Sterling Owen IV said. Police said they had found no connection between any of the women shot and the man, who has not been named.

Police spokesman Darrell DeBusk said investigators don’t think the suspect ever worked at the hospital.

Photographs of the discharge area, where vehicles can pick up patients, showed a man’s body lying face down, surrounded by police. Yellow crime tape was stretched around the area and police took photographs inside of the van taxi.

The two women who survived the shooting were taken to the trauma center at the University of Tennessee Medical Center. Spokeswoman Karen Bultman said Tuesday morning the women were in stable condition.

The women’s families issued statements expressing thanks for prayers and support.

The family of Ariane Reagan Guerin, a 26-year-old employee at Parkwest, said they were hearing promising information about her prognosis. The family of Nancy Chancellor, 32, said she was doing well.

The woman killed was Rachel Wattenbarger, 40. Her father, Ray Wattenbarger, said she had worked at the hospital for about five or six years, helping discharge the elderly. He said he would remember his daughter’s smile.

Linda Cody, whose father was a patient at the hospital, had gone to smoke a cigarette when she saw the gunman’s body, surrounded by blood. She quickly learned the victims had been shot in the same area where she normally smoked.

“It was scary,” she said. “It kind of gives you the willies thinking that could have been me five seconds ago.”

Charles Billingsley was taking his sister to a nearby doctor’s office and heard the shooting, though he wasn’t close enough to see the attack.

“I heard five pistol shots, back to back, and then another and then another,” Billingsley said. “I just saw people running from the hospital.”

Sakhleh, the cab driver, said he was lucky to be alive.

“My wife always tells me, ‘Be careful, be careful.’ But after tonight, I’m going to be real careful.”

(Associated Press writer Sheila Burke in Nashville contributed to this story.)