Live Blog: Deadly Shooting at Washington Navy Yard

Police work the scene near the Washington Navy Yard, Sept. 16, 2013.
A senior U.S. naval officer says four people are confirmed dead at a shooting at the Naval Sea Systems Command Headquarters in Washington, DC. Police say at least six others are injured in the shooting, first reported around 8:20 a.m. The news is rapidly evolving, with many unconfirmed details. This blog presents what is confirmed.

11:20 am Police update casualties. Officials say 12 people shot, at least four killed. Of the wounded, six are civilians, two are police offficers.

11:10 am Watch ABC 7 live stream of DC police press conference at 3rd and M Street South East, Washington, DC expected momentarily:

11:07 am Police say family members separated by crisis may reunite at National Stadium Parking Lot B.

11:00 am DC police expected to address press in next 15 minutes.

10:55 am Police lockdown six D.C. public schools and one administrative building as a precaution. Authorities are urging people in the area to stay inside.
Amidon-Bowen Elementary
Brent Elementary School
Eastern High School
Eliot-Hine Middle School
Jefferson Academy
Tyler Elementary School
Van Ness Administrative Building
10:45 am Interactive map showing the Naval Sea Systems Command Headquarters, where 3,000 people work:

10:40 am Authorities lift ground stop at Reagan National Airport

Flight operations return to normal at Reagan National after more than two dozens flights were put on temporary hold by the Federal Aviation Administration.

10:26 am Nearly two hours after first reports of shooting emerged, the area is still on lockdown.

The U.S. Navy says several people have been wounded in a shooting at the Washington Navy Yard.

A person with a gun was reported inside the Naval Sea Systems Command Headquarters building early Monday. Via Twitter, the Navy confirmed "several injuries with reports of fatalities." News reports say one of the wounded is a police officer.

Security personnel were searching for the shooter.

The White House announced that President Obama has been briefed on the situation.

The Washington Navy Yard is located about two kilometers from the U.S. Capitol.

The Naval Sea Systems Command's headquarters is the work place for about 3,000 people. The Command is in charge of engineering, building, buying and maintaining ships, submarines and combat systems.