Orlowski said the police officer was in the operating room with gunshot wounds to the legs. The police chief said he was wounded when he engaged the shooter. It wasn't clear if he shot at the gunman.
One woman had a gunshot wound to the shoulder. The other had gunshot wounds to the head and hand.
Anxious relatives and friends of those who work at the complex waited to hear from loved ones.
Tech Sgt. David Reyes, who works at Andrews Air Force Base, said he was waiting to pick up his wife, Dina, who was under lockdown in a building next to where the shooting happened. She sent him a text message about being on lockdown.
"They are under lockdown because they just don't know," Reyes said. "They have to check every building in there, and they have to check every room and just, of course, a lot of rooms and a lot of buildings."
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. Only security personnel were allowed to be armed on the campus.
Mason, the program management analyst for the Navy, said there are multiple levels of security to reach his office where he heard gunfire. Everyone must show their building IDs to get through a main gate, and at the building entrance, everyone must swipe their badges to pass through either a door or gate, depending on the entrance.
That "makes me think it might have been someone who works here," he said.
The Navy Yard has three gates, according to its website. One is open around the clock and must be used by visitors. A second gate is only for military and civilian Defense Department employees. The other gate is for bus traffic.
The Navy Yard is part of a fast-growing neighborhood on the banks of the Anacostia River in southeast Washington, just blocks from the Nationals Park baseball stadium.