(ABC News) At least four people are dead and multiple people are injured following a shooting at the Natalie Building at St. Francis Hospital in Tulsa, Oklahoma, on Wednesday, according to police.  Police received a call of a man walking with a rifle near a medical office shortly before 5 p.m. local time. When police responded, they said it turned into an active shooter situation, according to Tulsa Police Captain Richard Meulenberg.

When police entered the building, they found multiple people shot. “Officers immediately rushed to the second floor where the shooting was taking place, when they got there they found a few people had been shot, a couple were dead at that time,” Meulenberg told ABC News. “We also found at that time who [we] believe and still believe to [be] the shooter because he had a long rifle and a pistol with him.”

Tulsa police said the shooter died from an apparent self-inflicted gunshot wound.

One of the victims died after leaving the scene trying to seek medical aid, Meulenberg said. It is unclear at this time how many others were wounded in the shooting, though Meulenberg believed it to be under 10.

Police said they went through the five-story medical complex room by room to secure the building. “We are doing a meticulous floor-by-floor, room-by-room search … It’s calmed down. We’re trying to connect people and we’re hoping not to find any victims,” Meulenberg said.

President Joe Biden has been briefed on the shooting, the White House said. “The White House is closely monitoring the situation and has reached out to state and local officials to offer support,” the White House said in a statement.