Dana Vollmer swims the women's 100-meter butterfly on her way to winning the race during the U.S. National Championships. She gave her gold medal to Alexandria’s Cassidy Bayer. (Michael Conroy/ASSOCIATED PRESS)

Just a few months ago, it hadn’t occurred to Cassidy Bayer’s coaches or parents to send the 13-year-old swimmer to the U.S. National Championship and World Trials. At the time she had only qualified in one event — the 200-meter butterfly — achieved last summer when she broke the 11-12 national age group record in the event. But after three days in Indianapolis, Bayer has top-15 finishes in the 50-, 100- and 200-meter butterfly against the country’s best swimmers and a gold medal to take home to Alexandria with her.

The finishes were her own. The medal came from two-time Olympian Dana Vollmer, who won the women’s 100-meter butterfly on Thursday night.

“Cassidy went up and asked Dana for an autograph and got a picture of the two of them together,” said Emily Bayer, Cassidy’s mom. “Afterwards, Dana walked up and handed Cassidy her gold medal with a note written on the ribbon that said, ‘Keep swimming!’”

It was a special moment for the budding star at her first major national swim meet and left her in smiles for the rest of the meet as she walked around the pool deck signing autographs of her own.

Bayer was the second youngest swimmer at nationals, but like her more famous Nation’s Capital teammate, Katie Ledecky, Bayer is swimming beyond her years.

“Cassidy is that perfect combination of talent and work ethic that’s just really special,” said her coach, Jeff King. “I’ve never seen a swimmer at her age have ‘it’ like she does.”

Bayer won the “C” final of the 100 butterfly in 59.99 seconds. Bayer was .48 seconds off the 13-14 national age group record in the event.

It was her second “C” final victory of the meet. She also won the 200 fly on Tuesday. Vollmer watched from a monitor in the ready room. Two heats later, Vollmer dominated the event’s championship final in 57.53 to earn the medal she would pass on to Bayer.

Finished for the week, Bayer and her family are driving back to Virginia on Friday so Cassidy can compete for Mount Vernon Park in its second dual meet of the season in the Northern Virginia Swim League where she will ‘keep swimming’ as Vollmer told her, and perhaps down the road Bayer will pass a medal onto the next rising butterfly star.

Also competing on Thursday, three-time All-Met Swimmer of Year Jack Conger finished eighth in the men’s 100 butterfly. Eugene Godsoe and Ryan Lochte finished in first and second in 51.66 and 51.71.

Lochte said he is a closer and prefers to swim a 200-meter race to a 100-meter event, but is going to be training more in the 100 butterfly.

“I just have to believe in my training,” Lochte said. “I’ve trained really hard these past two months. It wasn’t close, but I have to hand it to everyone. They did really good.”

Rachel Bootsma won the 50 backstroke in 27.68 seconds to break the American and U.S. Open records, and Kevin Steel and David Plummer also set U.S. Open records.

Steel broke the 50 breaststroke mark that he set in the preliminaries, finishing in 27.26 seconds. Plummer won the 50 backstroke in a record 24.52.

“I really just tried to focus on my start and get off the block,” Bootsma said. “There are still some improvements I can make, but it’s my first time setting a record, so I’m really excited.”

Four-time gold medalist Missy Franklin — who already qualified in the 100 freestyle, 200 freestyle and 200 backstroke — was second in 27.98.

Steel edged Arizona club teammate Kevin Cordes.

In the 400 individual medley, Maya Dirado won in a career-best 4:34.34.

“The 400 IM is what I think about every day at practice,” Dirado said. “I was just really excited to do a race that I truly prepared for and had thought about a lot.”

Nineteen-year-old Chase Kalisz out of North Baltimore Aquatic Club won the men’s race in 4:11.83.

World record holder Jessica Hardy won the 50 breaststroke in 30.24 in the first year the event is being contested at the national championships.

The Associated Press contributed to this report.