Shooting at a medical building in Oklahoma state's Tulsa city leaves five people dead, including shooter who's believed to have taken his own life, authorities say.

Police responded to a call about a man with a rifle at St. Francis Hospital, which
Police responded to a call about a man with a rifle at St. Francis Hospital, which "turned into an active shooter situation," officials say. (AP)

A gunman has killed at least four people at a hospital campus in Tulsa, Oklahoma, police said, the latest mass shooting to convulse America coming as Texas families bury their dead after a school massacre barely one week ago.

The suspect, who was armed with a rifle and a handgun, was also killed in the attack on Wednesday at the St. Francis Health System hospital campus, police said.

"Right now we have four civilians that are dead, we have one shooter that is dead, and right now we believe that is self-inflicted," Tulsa Police Department Deputy Chief Eric Dalgleish.

He said officers responded immediately after emergency calls came in that a shooter had stormed into the second floor of a clinic attached to St. Francis. Police went floor by floor, room by room in an effort to clear the building during what authorities described as an active shooter situation.

Earlier, Tulsa police Captain Richard Meulenberg said officers were treating the scene as "catastrophic," with "several" people shot and "multiple injuries."

It was not clear how many other people might have been wounded. 

Dalgleish said the entire assault from the moment emergency calls came to the time officers engaged the shooter lasted about four minutes.

READ MORE: US to review police response to Texas school shooting

Deadly assaults 

The shooting is the latest in a string of deadly assaults by gunmen that have rocked the United States in the past month.

On May 14 a white supremacist targeting African Americans killed 10 people at a grocery store in Buffalo, New York. The shooter survived and is facing charges.

Ten days later an 18-year-old gunman armed with an AR-15 burst into an elementary school in the small Texas town of Uvalde and killed 21 people –– 19 of them young children –– before being shot dead by law enforcement.

On Wednesday one of the two teachers killed in that attack was laid to rest in Uvalde, a day after the first funerals for the children.

Gun regulation faces deep resistance in the US, from most Republicans and some rural-state Democrats.

But Biden -–– who visited Uvalde over the weekend –– vowed earlier this week to "continue to push" for reform, saying: "I think things have gotten so bad that everybody is getting more rational about it."

Some key federal lawmakers have also voiced cautious optimism and a bipartisan group of senators worked through the weekend to pursue possible areas of compromise.

They reportedly were focusing on laws to raise the minimum age for gun purchases or to allow police to remove guns from people considered a threat to themselves or others –– but not on an outright ban on high-powered rifles like the weapons used in Uvalde and Buffalo.

READ MORE: Several killed in ‘racially motivated’ shooting at New York supermarket

Source: TRTWorld and agencies