Tulsa hospital shooting: A timeline of the shooting at Saint Francis campus that left 5 dead

Tulsa police on Thursday provided a detailed description of the mass shooting Wednesday at a Tulsa medical center that left two doctors, an office receptionist and a visitor dead before the gunman killed himself.

The gunman opened fire about 4:52 p.m. at the Natalie Building of the Saint Francis Health System campus, shooting the four people using at least two firearms — a rifle or "long gun" and a handgun, according to Tulsa police.

Photos: Tulsa police give shooting update on Thursday

Here is a timeline of events leading up to and including the time during the shooting at Saint Francis as described by Tulsa Police Chief Wendell Franklin.

Days leading up to the Tulsa shooting

May 19: Dr. Preston Phillips, an orthopedic surgeon, performs back surgery on Michael Louis in Tulsa.

May 24: Louis is released from the hospital. In the days after his release, he contacts Phillips' office several times seeking further treatment for pain.

May 29: Louis buys a semi-automatic handgun at a pawn shop in Muskogee.

May 31: Phillips sees Louis again in his Tulsa office for additional treatment.

Day of the Tulsa shooting, June 1

June 1: Louis calls Phillips' office again seeking more treatment for continued pain.

Read: Tulsa shooting draws reactions from Oklahoma lawmakers, elected officials

About 2 p.m.: Louis buys an AR-15 style semi-automatic rifle at a Tulsa gun store.

4:52 p.m.: Someone on a video call with a doctor at Saint Francis calls police after the doctor on the video call told the person there was a shooting taking place at the hospital.

4:53 p.m.: Multiple 911 calls are made to Tulsa police reporting a shooting at Saint Francis.

4:55 p.m.: Callers to 911 say the shooting is on the second floor of the Natalie Medical Building at Saint Francis.

4:56 p.m.: The first Tulsa police officers arrived at the Natalie Medical Building. The officers go the second floor and begin shouting, "Tulsa Police!"

4:58 p.m.: The officers hear a single gunshot, which is believed to be the shot Louis fired to kill himself in the waiting room. Officers find one victim next to Louis.

A woman who survived is found hiding under a desk near Louis' body. Phillips is found dead in an examination room. Another victim is found dead near a nurses' station. A shooting victim found in another examination room is taken to the hospital and dies there.

About 5:30 p.m.: The Cherokee County sheriff's office contacts Tulsa police to say a woman has reported her husband intended to kill Phillips. A letter found on Louis' body "made it clear he intended to kill Dr. Phillips," Chief Franklin said.

About 7 p.m.: The Muskogee Police Department says it was notified by Tulsa police that the shooter may have planted a bomb at a Muskogee home. Muskogee police notified nearby residents and prepared to search the house.

About 9:30 p.m.: Muskogee police say the Oklahoma Highway Patrol bomb squad used a bomb dog to determine there was no explosive device inside the home. The scene was turned over to Tulsa police investigators, Muskogee police said.

What we know: Tulsa medical center shooting

The aftermath of the Tulsa shooting

3 a.m. on June 2: Homicide detectives and other investigators finish working the crime scene, which is tuned back to Saint Francis officials.

This article originally appeared on Oklahoman: A timeline of the shooting spree at a Tulsa hospital that left 5 dead