The attacker then turned the gun on himself, police said in what is the latest in a string of mass shootings in the US.
Tulsa Police Chief Wendell Franklin said in a news conference later on Thursday, that Dr. Preston Phillips, Dr. Stephanie Husen, Amanda Green and William Love were all killed in the inicdent in the medical bulding of Saint Francis Hospital.
Mr Frankling added that the attacked had been seen for treatment on Tuesday and called the hospital complaining of back pain and insisted on further assistance.
“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,” Mr Franklin said. “He blamed Dr. Phillips for the ongoing pain following the surgery.”
The other medical professionals were killed as they stood in the way of Dr Phillips, just hours after the attacker pruchased an AR-style rifle.
Police arrived at the St. Francis Hospital campus three minutes after receiving a call about the shooting on Wednesday. Officers followed the sound of gunfire up to the Natalie Building’s second floor, Tulsa’s deputy police chief Eric Dalgleish said.
The officers made contact with the victims and the suspect five minutes later, Mr Dalgleish said.
Police responses have come under intense scrutiny after a teenage gunman killed 19 children and two teachers at Robb Elementary School in Uvalde, Texas last week while local officers waited outside in the hallway for nearly an hour.
Asked whether police had refreshed training or thinking about active shooters after the Uvalde school shooting, Dalgleish said: “I think that’s probably fresh on everyone’s minds.”
“I will say Tulsa revisits that topic regularly. I was very happy with what we know so far regarding the response of our officers,” Dalgleish said.
Wednesday’s incident in Tulsa came on the heels of mass shootings that have reignited debates about gun control in America.
Two weeks before the Uvalde mass school shooting, a white gunman killed 10 people at a supermarket in a Black neighborhood in Buffalo, New York.
The White House said President Joe Biden had been informed about he shooting and offered support to state and local officials in Tulsa.
The city, home to around 411,00 residents, is around 100 miles northeast of the state capital, Oklahoma City.