Navy Yard Shooting UPDATE: At Least 12 People Confirmed Dead

One shooter is dead on Monday morning at the Washington Navy Yard shooting incident and authorities are investigating the possibility of additional shooters wearing military-style uniforms, Metropolitan Police Chief Cathy Lanier confirmed.

At least one gunman opened fire inside a building at the Washington Navy Yard on Monday morning, and officials said 12 people were killed and at least four were wounded, including a law enforcement officer.

“The big concern for us right now is that we potentially have two other shooters that we have not located at this point,” Washington Police Chief Cathy Lanier told reporters.

Lanier said authorities were looking for a white man and a black man in military-style clothing who could be connected to the shooting.

“We have no information to believe that either of those folks are military personnel, but we do have information that those individuals are wearing military-style uniforms,” she said.

Earlier Monday, Ed Zeigler, director of public affairs for Naval District Washington, told CNN that two suspected shooters were “down,” but a senior Navy official could not confirm whether there was more than one gunman.

Multiple people were killed in the deadly shooting, Zeigler said, which sent police in SWAT team gear swarming to the scene.

Helicopters hovered overhead. In one chopper, there appeared to be a police sniper peering out, with a scope at the ready.

Earlier, authorities said a gunman dressed in all black fired shots inside the Navy Yard, injuring at least 10 people.

The injured included a Washington police officer who has been hospitalized, and a base security guard officer, said Metropolitan Police Department spokeswoman Saray Leon.

Three people, including the D.C. police officer, were admitted to MedStar Washington Hospital Center with multiple gunshot wounds. They are expected to survive, chief medical officer Janis Orlowski told reporters.

The incident started unfolding at 8:20 a.m. when several shots were fired inside the headquarters for Naval Sea Systems Command in southeast Washington.

The Bureau of Alcohol, Tobacco, Firearms and Explosives sent a team of about 20 special agents to the scene, a law enforcement official said. The team was the same group that helped apprehend Boston Marathon bombing suspect Dzhokhar Tsarnaev, the official said.

Police spokesman Chris Kelly earlier described the suspect as an adult male, about 6 feet tall with a bald head and medium complexion, dressed in a black top and black jeans.

Two witnesses told CNN affiliate WJLA that they heard a fire alarm go off in the building where they worked, then saw a man with a rifle down the hallway as they exited the building.

“He aimed the gun and fired our way,” a man who identified himself as Todd Brundidge told WJLA, adding, “I couldn’t believe it.”

People frantically tried to run out of the building, Brundidge said.

“Everyone was going down the stairs. They were pushing. They were shoving. People were falling down,” he told WJLA. “As we came outside, people were climbing the wall trying to get over the wall to get out of the spaces. It was just crazy.”

Emergency personnel, the FBI, U.S. Capitol Police and local D.C. police responded to the shooting, shutting down traffic in the area on the District’s south side along the Anacostia River. Some people are being evacuated, and others are sheltering in place.

Security was stepped up at the Pentagon.

At least eight schools were on lockdown as a precaution, the Washington public schools said.

Air traffic to Reagan National Airport in northern Virginia, the closest airport to downtown Washington, was suspended but later resumed, the Federal Aviation Administration said.

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