WASHINGTON — In Building 197, the bustling headquarters of the Naval Sea Systems Command in Washington, Navy Capt. Mark Vandroff was running a meeting.
"I had a very routine day planned for myself," he said.
That changed shortly after 8:15 a.m. when gunshots rang out — first a few, then a fusillade. The building erupted in pandemonium.
On the fourth floor, Navy Cmdr. Tim Jirus heard what sounded like muffled gunshots. After helping evacuate workers, he was outside in an alleyway when a maintenance worker told him the shooter was still in the building. As Jirus stood next to him, the worker was shot in the head.
"I'm fairly certain he was dead," said Jirus, who ran for cover.
FULL COVERAGE: Navy Yard shooting
Employees described carnage at the naval administrative complex alongside the Anacostia River in southeast Washington.
Although access is closely controlled, employees said, they do not have to pass through metal detectors. Workers must first present their military ID cards to an armed security guard at the entrance to the compound, which is about a mile from the Capitol.
To enter Building 197, an employee swipes the card over an electronic reader, and a green light signals the person is cleared to enter.
Gary Humes, a program manager, said he was nearing the building entrance when he heard a blast and saw people running out the door. He took shelter across the street in Building 201.
He had come to work a few minutes late. "I guess God was on my side on that one," Humes said.
Vandroff, manager of the Navy's non-nuclear surface ships, was running a routine meeting in a third-floor conference room when he heard gunfire, looked up and saw two bullet holes in the wall near the ceiling. Everyone pushed tables against the doors, then hit the floor and stayed as flat as they could, he said.
Vandroff said they heard intermittent gunfire for about 40 minutes, until a police team checked their identities and cleared them to leave.
PHOTOS: At the scene of Navy Yard shooting
His staff members were safe, he said, but a friend was killed.
"I know I lost a friend today," Vandroff said. "I haven't processed that yet. I don't know how you process something like this. I count myself lucky to be out here."
The neighborhood remained locked down much of the day, with children sheltered in schools and flights suspended for a time at Reagan National Airport. Police turned a parking lot at the nearby baseball stadium, Nationals Park, into a family meeting area. A game for the playoff-contending Washington Nationals was postponed.
Weary-looking employees straggled away from the complex, talking on cellphones and stepping around the power cords that led to a horde of media satellite trucks.
A steady stream of people began leaving about 4 p.m., walking briskly down M Street toward the metro station. Most did not want to comment on their experiences, except to say they just wanted to get home.
Jacqueline Alston, 63, arrived to look for her husband, Ernest Johnston, a custodian. She hadn't heard from him.
"They just told me to be patient," she said. "I'm numb, I'm talking, I'm worried, but I know God is the answer."
Doug Hughes, who works on the first floor of Building 197, said he and a co-worker had locked themselves inside an office when they heard the shots.
Now, he was on his way to the family area to meet his wife, but he didn't know what he was going to say to her.
"I'm just going to hug her," he said.
David Cloud and Brian Bennett in the Washington bureau contributed to this report.