Thursday's shooting at a medical institution in Tulsa, Oklahoma, resulted in the deaths of four victims and the alleged shooter, authorities said.

On the St. Francis medical campus, officers rushed to a report of a suspect armed with a rifle, which "developed into an active shooter incident." 

During a news conference, Deputy Chief Eric Dalgleish of the Tulsa Authorities Department confirmed the number of fatalities and stated that the suspected gunman took his own life.

It was unknown what triggered the violent attack.

The events in Tulsa are an act of senseless violence and hatred, said Oklahoma Governor Kevin Stitt in a statement.

"I am thankful for the swift and courageous actions of the Tulsa Police Department and other first responders who did everything they could to control a horrible situation," Stitt said.

"I ask all Oklahomans to assist Saint Francis Health System and mourn alongside victims whose lives have cruelly been affected," he stated.

Dalgleish did not disclose the name of the alleged shooter, but authorities discovered that he was in possession of both a rifle and a handgun, and it looked that both were shot at the site.

On Wednesday afternoon, St. Francis Health System closed down its campus due to the incident at the Natalie Medical Building. The police reported that officers were searching each room in the building.

The Natalie building comprises a breast health center and an outpatient surgery center. Dalgleish stated that at least a portion of the incident occurred on the second level at an orthopedic center. The public was instructed to avoid the area.

At the news conference, Tulsa's mayor, G.T. Bynum told reporters, "this place is holy ground for our community... this campus has been a site where heroes have worked every day to save the lives of community members for decades."

Bynum said he would like people to consider the significance of the St. Francis Health System and its employees to the community, families and neighbors.

Tulsa police stated they were attempting to identify the culprit, who they estimated to be between 35 and 40 years old, but had no information regarding his motivation.

Dalgleish claimed that the Natalie Building contained medical offices, including an orthopedic facility, and that he believed the victims comprised both personnel and patients.

The White House indicated that President Joe Biden had been briefed on the shooting and provided support to state and local officials in Tulsa, a metropolis of approximately 411,000 people.