Shooter in Tulsa medical center attack targeted his doctor after surgery left him in pain, police

The suspect in the recent Tusla, Oklahoma, medical center shooting targeted his back doctor, after the doctor recently  performed a surgery on him resulted in ongoing pain, officials said Thursday.

The Tulsa Police Department also said the gunman bought an AR-style rifle one hour before opening fire Wednesday at the center, killing the surgeon and three other people before fatally shooting himself.

Tulsa Police Chief Wendell Franklin identified the alleged gunman as Michael Louis, 45, of Muskogee, Oklahoma. The suspect underwent back surgery on May 19 and subsequently called the clinic repeatedly to complain about pain.

He identified the doctor who performed the surgery as Dr. Preston Phillips, who was shot and killed along with Sports Medicine Dr. Stephanie Husen, receptionist Amanda Glenn and patient William Love, according to the Associated Press.

He also said authorities also have a letter that makes clear the gunman "came in with the intent to kill Dr. Phillips and anyone who got in his way," the wire service also reports.

Police said they recovered thirty .223-caliber shell casings, as well as a rifle of that caliber on the scene, and seven .40-caliber casings, along with a pistol with that caliber. Detectives also found a note on the suspect explaining his actions that day.

Authorities said the gunman carried a rifle and handgun during the shooting at the medical building, on the Saint Francis Health System hospital campus, the latest in a series of deadly mass shootings across the country in recent weeks.

The shooter died from an apparent self-inflicted gunshot wound, Tulsa Police Department Deputy Chief Eric Dalgleish said.