A shooter wanted in connection with a Monday morning shooting at the Washington, D.C. Navy Yard that left four people dead and six others wounded has been killed.
It's possible another gunman could be at large.
A large search, including from helicopters, was still underway. "It's a large piece of land with many buildings," Assistant D.C. Police Chief Peter Newsham told News4. "It's going to take a while."
Tactical teams have entered at least two buildings on the Navy Base to search for the shooter, and News4's Mark Segraves reported that three helicopters were seen tightly circling part of the base.
One of those shot was a D.C. police officer, reported NBC News' Pete Williams. Another was a base security officer.
The conditions of the victims are unknown, but George Washington Hospital reported that at least two victims have been transported to that hospital.
The U.S. Navy said the shooting began at about 8:20 a.m. with three shots fired inside Building #197 at the Naval Sea Systems Command Headquarters, 1336 Isaac Hull Ave. in the Southeast section of the District. U.S. military officials say the gunman first shot the base security officer. Police confirmed that there was no AR-15 assault rifle used, as previously reported.
One victim was reported to be on the roof of a building, reported News4's Tony Tull. A U.S. Park Police helicopter hovering above the scene around 9:50 a.m. lowered a basket to a building and lifted what appeared to be a shooting victim from the roof. The helicopter came back to the scene just after 10 a.m. to retrieve another victim.
But other details were sketchy from the still-active scene. The shots continued to ring out through the morning, including a volley that Tull reported at about 9:20 a.m. and another volley that News4's Mark Segraves heard at about 11 a.m.
Authorities originally believed there was a lone gunman, but sources later confirmed to News4 that the shooting was carried out by at least two gunmen.
Federal and local emergency personnel converged on the scene, "and a shelter in place order has been issued for Navy Yard personnel," the Navy said. Among the responders was a federal SWAT unit.
President Barack Obama is getting frequent briefings about the deadly shooting from senior aides. The White House says Obama directed his team to stay in touch with the Navy, FBI and local officials as the events unfold.
D.C. Public Schools put six schools and one administrative building on lockdown, meaning no visitors or staff may enter or leave the building and recess for students is inside. These schools are affected:
- Amidon-Bowen Elementary School
- Brent Elementary School
- Eastern High School
- Eliot-Hine Middle School
- Jefferson Academy
- Tyler Elementary School
- Van Ness Administrative Building
The following charter schools are also on lockdown:
- Eagle Academy PCS - New Jersey Ave.
- Friendship PCS Chamberlain Elementary and Middle.
- Cesar Chavez PCS for Public Policy - Capitol Hill
- Richard Wright PCS for Journalism and Media Arts
- Somerset Prep DC PCS
The 11th Street Bridge and roads in the area are closed.
Metro has also reopened New Jersey Avenue entrance at the Navy Yard station.
The Navy Yard is located in southeast Washington on the Anacostia River. The Navy says 3,000 people work inside the building, including command staff, headquarters directorates and field activities. They coordinate the Naval Sea Systems Command, or NAVSEA, the largest of the Navy's five system commands.
Stay with NBCWashington on-air and online for more on this developing story.