TULSA - A gunman has killed at least four people at a hospital building in Tulsa, Oklahoma, police said -- the latest in a string of mass shootings across the United States in recent weeks.

The killings come as Texas families bury their dead after a school shooting left 19 young children dead just eight days earlier.

The Tulsa shooting suspect, who was armed with a rifle and a handgun during his attack on the Saint Francis hospital campus, died by suicide, police said Thursday.

“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 told reporters. He said officers responded immediately after emergency calls came in reporting that a gunman had stormed into the second floor of the Natalie Building, which houses a clinic on the Saint Francis campus.

Police “were hearing shots in the building” when they arrived, according to Dalgleish, who said officers then searched each room and floor while trying to clear the building during what authorities described as an active shooter situation. Police Captain Richard Meulenberg said officers treated the scene as “catastrophic,” with “several” people shot and “multiple injuries.” It was not clear how many other people might have been wounded.