A gunman who opened fire at a Tulsa clinic killing four, targeted a surgeon he blamed for ongoing back pain after a recent surgery.
Tulsa Police Chief Wendell Franklin said the suspect, who shot himself after the attack, had called the Saint Francis Health System repeatedly to complain of pain.
"We also have a letter on the suspect, which made it clear that he came in with the intent to kill Dr. Phillips and anyone who got in his way," Franklin said. "He blamed Dr. (Preston) Phillips for the ongoing pain following the surgery."
The victims, another doctor, a receptionist and a patient, were found alongside the gunman on the second floor of a medical office, where an orthopedic clinic is located, police said.
The hospital said in a statement that it was "grieving the loss of four members of our community" but did not immediately identify the dead.
Police said the gunman bought the rifle used in the shooting more than two hours earlier. He also purchased a handgun May 29.
Some information in this report comes from The Associated Press.