ATLANTA (AP) — A man opened fire outside the headquarters of the U.S. Centers for Disease Control and Prevention in Atlanta on Friday, leaving bullet impacts in windows across the sprawling campus and killing a police officer before he was found dead in a nearby building, authorities said.

The attack, which unfolded near the neighboring Emory University campus, prompted a massive law enforcement response to one of the nation’s most prominent public health institutions, but no one else was reported to be injured.

Images shared by employees showed multiple CDC buildings with bullet-pocked windows, underscoring the breadth of the damage to a site where thousands of scientists and staff work on critical disease research.

The gunman was found on the second floor of a building across the street from the CDC campus and died at the scene, Atlanta Police Chief Darin Schierbaum said. He added that “we do not know at this time whether that was from officers or if it was self-inflicted.”

The shooter was armed with a long gun, and authorities recovered three other firearms at the scene, according to a law enforcement official who spoke on the condition of anonymity because they were not authorized to discuss the ongoing investigation.

The gunman’s motive is still unknown this early in the investigation, Atlanta Mayor Andre Dickens said.

Police declined to name the officer who was killed, but DeKalb County CEO Lorraine Cochran-Johnson struck at the emotions of the loss.

“This evening, there is a wife without a husband. There are three children, one unborn, without a father,” Cochran-Johnson said.

When the shooting kicked off, staff at a nearby restaurant hunkered down and said they heard a string of gunshots. “It sounded like fireworks going off, one right after the other,” said Brandy Giraldo, the chief operating officer of The General Muir restaurant.

She then saw people running past her business. Two people paused to warn them of a shooter nearby.

The CDC and Emory’s main campus are surrounded by affluent wooded neighborhoods in northeast Atlanta. All three institutions line up along Clifton Road. The area is hard to access, and notoriously traffic-choked, but on Friday few cars were in evidence as a warning siren blared.

Gov. Brian Kemp praised the efforts of first responders.