A man carrying a rifle and a handgun opened fire in a medical office building in Tulsa, Okla., on Wednesday afternoon, killing four people before apparently taking his own life in the latest mass shooting to shock the country, the authorities said.

At a news conference on Wednesday night, Eric Dalgleish, deputy chief of the Tulsa Police Department, said it was unclear whether the gunman had been targeting someone in particular.

Austin Breasette, a reporter at KFOR, showed a view of the scene at 61st and Yale. “The death toll has now reached 5 including the shooter who died from a self-inflicted gunshot wound. Police say the other victims could be a combination of staff and patients.”

According to the NY Times, the gunman’s identity had not been determined, but he was between 35 and 40 years old, Chief Dalgleish said.

The police received a call about a shooting at 4:52 p.m., and they arrived at the scene four minutes later, Chief Dalgleish said. He also said that all of the gunfire is believed to have taken place in one section of the Natalie Building’s second floor. The sound of gunfire drew officers to that area.

Mayor G.T. Bynum of Tulsa said at the news conference that some of the families of the victims had not yet been informed about what had happened.

“This has been the facility more than any other that has worked to save the lives of people in this city,” Mr. Bynum said. He praised “the broad range of first responders today who did not hesitate to respond to this act of violence.”