The Tulsa hospital shooter has been identified as 45-year-old Michael Louis.

Originally reported by Breaking911, police say Louis killed four people with a rifle Wednesday and was targeting a doctor who recently performed surgery on him. Louis then produced a handgun and took his own life, police said.

Tulsa Hospital Shooting Suspect Michael Louis

The gunfire broke out around 5:00 PM local time at the Natalie Medical Building at Saint Francis Health System in Tulsa.

Dr. Preston Phillips was Louis’ main target, police said. Adding, he was shooting anyone who “stood in his way.”

The other victims were identified as Dr. Stephanie Husen, Amanda Glenn, a receptionist, and William Love, a patient.

Watch Press Conference, Police Give Possible Motive In Tulsa Shooting:

Police Chief Wendell Franklin said officers located a letter on Louis that “made it clear that he came in with the intent to kill Dr. Phillips and anyone who got in his way. He blamed Dr. Phillips for the ongoing pain following the [back] surgery.”