Story highlights Vice President Mike Pence officiated, a source told CNN

The wedding, which was attended by about 300 guests, was "elegant," a source said

(CNN) President Donald Trump and Vice President Mike Pence were among the throng of Washington power players attending Treasury Secretary Steve Mnuchin's wedding to Scottish actress Louise Linton on Saturday evening.

But Pence didn't just attend -- he officiated, a source told CNN.

The nuptials took place at the historic Andrew W. Mellon Auditorium in Washington, DC. The bride wore a white gown with a lace top and full skirt and a diamond tiara; the groom, black tails and white bow tie. The first lady, meanwhile, donned a flowing pale pink evening gown and the President, a classic black tuxedo, the source said.

Guests at the wedding, who were expected to include Trump's son-in-law Jared Kushner, first daughter Ivanka Trump and several Cabinet members, were treated to a performance by kilted bagpipers and ballerinas in white tutus, the source said.

The wedding was attended by about 300 guests, many bussed in by private charter from Trump International Hotel; it was an "elegant" affair, with lots of white flowers and white drapery, a source said. Wedding planner Lauryn Prattes handled the event, with Amaryllis, a company known for its dreamy floral designs, arranging the flowers.