Beyonce, Solange Knowles Celebrate Past 1 A.M. at Met Gala After Party

Beyonce Knowles attends the "Schiaparelli And Prada: Impossible Conversations" Costume Institute Gala at the Metropolitan Museum of Art on May 7, 2012 in New York City. Credit: Kevin Mazur/WireImage.com

Girls' night at the Boom Boom Room with Beyonce and Solange!

Surrounded by dozens of A-listers -- Gerard Butler, January Jones, Kirsten Dunst and beau Garret Hedlund, Lily Collins, Kristen Stewart, Ian Somerhalder and Nina Dobrev, Emma Roberts and more -- the singer and Blue Ivy's mom, 30, was the biggest star of them all at Prada's "after after party" for Monday's Met Gala, held at the Boom Boom Room at the Standard Hotel in downtown Manhattan.

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With sister Solange Knowles as her date and other pals, the "Love on Top" singer provoked a big stir with the crowd as she arrived past midnight.

With husband Jay-Z sitting this one out, the mother to Blue, 5 months, was in a great mood as her posse took over a couple private tables, where they sat and briefly grooved to the music.

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Beyonce stole the show earlier that night on the red carpet at the Metropolitan Museum of Art, wearing a sexy, sheer Givenchy Haute Couture gown w! ith simp le makeup and her hair pulled back into a sleek ponytail; Solange, 25, wore a canary yellow Rachel Roy dress.

While some well-wishers were turned away from the super-VIP table by a bodyguard, the sisters and their friends gabbed for an hour, with Beyonce sipping a martini with three olives.

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Their night at the Boom Boom Room wrapped up around 1:15 a.m., with the Knowles girls making a hasty exit.