Police did not say whether the attacker, who was armed with a rifle, was shot by security officers or killed himself.
“We can confirm that 4 people were killed, including the shooter, in an active shooting situation on the St. Francis Hospital campus. Officers are still clearing the building,” Tulsa police tweeted from their official account, adding that they will expand the information.
Earlier, police Capt. Richard Meulenberg said officers were treating the scene as “catastrophic” with “several” people shot and “multiple injured.”
The Joe Biden administration, informed of the shooting, offered support to local officials in a statement.
The incident is the latest in a series of deadly attacks by gunmen in the past month in the United States.
Just over a week ago, a young man armed with an AR-15 assault rifle stormed into a school in Uvalde, Texas, killing 19 children and two teachers, before being shot dead by law enforcement.
Controlling access to firearms in the United States, a right guaranteed by the second amendment to the Constitution, faces deep resistance from most Republicans and some rural Democratic states.
But Biden, who visited Uvalde over the weekend, pledged earlier this week to “keep pushing” for reform.
The entrance At least four killed in US shooting, including attacker was first published in diary TODAY.
