WASHINGTON - Washington D.C. police say at least 12 people have died in the shootings at the Washington Navy Yard.
D.C. Police Chief Cathy Lanier provided an update during a news conference Monday that 12 people were confirmed dead, opposed to about a half-dozen as previously reported.
Lanier says people are being told to stay in their homes and out of the area as authorities search for other possible suspects. One of the shooters has died -- identified as 34-year-old Aaron Alexis of New York City .
The police chief says officers were searching for people with firearms wearing military-style uniforms. At least one of those suspects matching that description was reported to be in the clear later Monday afternoon.
She says there is no indication of a possible motive at this time.
Lanier says one police officer was wounded in an exchange of gunfire with a shooter. She says that officer is in stable condition.
As many as 3,000 people work in the building. According to the the U.S. Navy, the shots were fired around 8:20 a.m. at the Naval Sea Systems Command. Naval Sea Systems Command is the largest of the Navy's five system commands and accounts for a quarter of the Navy's entire budget. It builds, buys and maintains the Navy's ships and submarines and their combat systems.
Patricia Ward , a logistics management specialist, said she was in the cafeteria at the US Navy Yard and heard at least seven shots.
"Pop, pop, pow" was followed by a pause and several more shots, she said. "We all panicked, and we were trying to decide which way we were going to run out. The workers in the cafeteria wanted us to stay in there and hide, but I just ran. A few of us just ran out the side exit."
Ward said she heard a shooter was on an upper level of the building, shooting down into the atrium.
Authorities originally identified the dead shooter as a Navy employee whose work status had been changed earlier this year. It was later learned Alexis got into the Navy Yard by using someone else's identification card . It is not yet clear if that individual was an accomplice or if that person's ID card was stolen.
Emergency personnel remain on scene and a "shelter in place" order has been issued for Navy Yard personnel.
Police and federal agents from multiple law enforcement agencies responded to the scene. Ambulances were parked outside, streets in the area were closed and flights at Reagan National Airport were temporarily halted.
A U.S. Park Police helicopter hovered over the building and appeared to drop a basket or a stretcher with a person onto the roof.
The White House says that President Barack Obama is getting frequent briefings on a shooting at the Washington Navy Yard. The White House added that Obama directed his team to stay in touch with the Navy, FBI and local officials.
Prior to a news conference scheduled to discuss the state of the economy, Obama promised to make sure that, "whoever carried out this cowardly act is held responsible." The president said the victims were "courageous Americans" who knew about the risks of serving overseas, but wouldn't have expected such "unimaginable violence" at home.
Later Monday, President Obama ordered flags lowered for the shooting victims .
In addition, the Coast Guard has established a temporary safety and security zone in response to the shooting. The zone will be in effect for an undetermined amount of time and will limit all navigation on the Anacostia River from Haines Point to the John Philip Sousa Bridge.
Entering or operating in the security zone is prohibited unless authorized by the captain of the port of Baltimore. Vessels already at berth, mooring or anchor are not required to depart the security zone.
"This zone is necessary to safeguard persons and property from events unfolding at the Washington Navy Yard," said Lt. Cmdr. Richard Armstrong, the chief of Incident Management at Coast Guard Sector Baltimore in a statement. "Our thoughts and prayers are with those persons and families involved in today's incident."
Also, according to the Navy, the Washington D.C. Metro Police Department is advising family members of Washington Navy Yard employees to meet their loved ones at Nationals Stadium Parking Lot B, South Capitol & K St SE.
Family members looking for information about their loved ones can contact the Warfighter and Family Support Center at 202-433-6151 or 202-433-9713.