A man who allegedly entered Fresno Police Department headquarters downtown and attacked a veteran detective was shot and killed by the officer at about 11:45 a.m. on Tuesday, according to Police Chief Paco Balderrama.

The alleged attacker died at the scene. The detective was taken to Community Regional Medical Center for treatment of lacerations to his head and neck, the chief said.

“He did give a thumbs-eye,” indicating that the detective was OK before going to the hospital, Balderrama said.

The chief added that the attacker’s identity was unknown, as was his motive for the attack: “I don’t know if he used a knife or it was something on the officer’s desk.”

He described the detective as in his 40s or early 50s and being smaller in stature. The attacker, according to Balderrama, was about 6 feet tall and in the vicinity of 300 pounds.

“He really had no business here,” Balderrama said of the attacker. “It’s troubling to me that a person with those intentions could enter police headquarters and intend harm to one of my officers.”

Balderrama also said that he viewed the office where the attack happened and it was “in terrible condition.”

The fatal shooting will be investigated by the Fresno County District’s Attorney’s Office and reviewed by the city’s independent police auditor, the chief said.

In addition, PD’s command staff will find out how the suspect gained entry and recommend measures to improve headquarters security.

Watch: Police Chief Balderrama’s Briefing on Officer-Involved Shooting