People who had phones were able to get updates, and different stories circulated about whether there were two or four shooters, and whether the shooting was a terrorist attack.
She said bathrooms and drinking water were available in the museum, but the only food available was what employees were able to carry with them.
Richardson said those who had their lunches "shared granola bars and things like that throughout the day."
She said FBI SWAT agents passed through the museum about two hours after the employees arrived to sweep the building, and then returned around 3:30 p.m. to bring those who had sought refuge there to another facility for interviews.
Richardson said she was asked where she was when the shooting started, and what she had heard or seen.
She was then taken by bus to Nationals Park, the home of the Washington Nationals baseball team, which is about a mile and a half west of the Navy Yard.
Richardson spent about an hour waiting for her daughter to pick her up; representatives of the American Red Cross were on hand, and Navy Secretary Ray Mabus spoke with her and other Navy Yard staff.
She told Mabus that she had been on the third floor and left down a stairwell, and the Navy secretary told her he spoke with a wounded victim who had been shot while coming down a stairwell in the same building.
"That could have been anybody, I guess," Richardson said.
Richardson was at home in Bel Air Tuesday, and gathering information about when she could return to work.
She did not expect to be back for several days, and thought "everybody will be uneasy for quite a while."
Richardson, as a new employee, did not know anyone who was wounded or killed in the shooting.
She had noticed that her co-workers are "very friendly, and it's like a family there."
"They look out for each other and take care of each other, so I think they'll be able to get through it," she said.
Outside looking in
Richardson's daughter Yi didn't realize Monday morning when she posted a message on Facebook about saying prayers for the people involved in the shooting at the Washington Navy Yard that her mother was among that group.
It wasn't until almost noon that Richardson, who had only recently begun making the commute from Bel Air to D.C. for her new job, replied on the social media site with something like, "Yeah, including your mother, I'm on lockdown."
Yi, a former editorial assistant at The Aegis, is from Aberdeen, but lives in Beltsville. She first heard news of the shooting while she was at work at Lakeside Veterinary Center in Laurel, where she spends most of her waking hours. She also is a regular at CrossFit Laurel.
She was in the lobby of the veterinary center listening to talk radio with her colleagues when she heard the news.
"I heard there was a shooting in the Naval Yard. And it took me a minute, because my mom's new there, but I thought, isn't mom's job at the Navy Yard? I wasn't sure what building she was in," Yi said. "I thought to myself, it will be OK, I'm probably getting worked up over nothing. It's probably not her building."