Four people were killed after a shooter opened fire inside a medical building at a Tulsa, Oklahoma, hospital campus on Wednesday, officials said.
The shooter is also dead, Tulsa police said, of an apparent self-inflicted gunshot wound.
Tulsa police officers were dispatched to St. Francis Hospital just before 5 p.m. after receiving a call about a man armed with a rifle in the Natalie Building at the hospital complex.
The incident prompted a massive police response, with dozens of cars surrounding the campus.
Deputy Chief Eric Dalgleish said the call came in at 4:56 p.m. and officers arrived at the hospital within three minutes.
The first officers on the scene heard gunshots coming from the second floor of the building, where they encountered the shooter and found the four victims, police said.
In a statement released Wednesday night, St. Francis Hospital declined to identify the victims but said it is "grieving the loss of four members of our community." The hospital also said the orthopedic office on the second floor would be closed until further notice.
The suspect, who was armed with one long gun and a handgun, is believed to have killed himself at the scene, Dalgleish said. Authorities are still working to confirm the identity of the shooter, he added.
Tulsa police captain Richard Meulenberg told the Washington Post that the shooter had "purpose" and "didn’t go in there and randomly pick the second floor of the facility to start shooting people."
Police continued searching the building for about two hours, going room by room. Local TV news aerial footage showed armed officers searching one building's roof.
The hospital shooting took place in what was been a dark, deadly month, with multiple mass shootings plaguing the country.
On May 14, a shooter opened fire in a Buffalo, New York, supermarket, targeting Black shoppers and killing 10 people in what has been deemed an act of domestic terrorism. On Wednesday, the suspect was indicted by a grand jury on charges including domestic terror and murder as a hate crime.
Ten days later, 21 people were killed in a shooting at a Uvalde, Texas, elementary school, including 19 children.
The American Public Health Association says gun violence in the US is a public health crisis. It is a leading cause of premature death in the country, responsible for more than 38,000 deaths annually. As of June 1, at least 18,086 people have died from gun violence this year, according to data from the Gun Violence Archive.