At least three people were killed and multiple injured following a shooting in a hospital in Tulsa, Oklahoma, on Wednesday, according to police.

"We know there are multiple injuries, and potentially multiple casualties," The Tulsa Police Department said in a statement quoted by ABC News.

The incident took place at the Natalie Building at St. Francis Hospital.

Police received a call of a man walking with a rifle near a medical office. 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.

The Tulsa Police Department said the shooter is dead but it remains if he was shot by police.

"Officers are currently going through every room in the building checking for additional threats," the department added.