Sofia Vergara's Post-Split Partying with Jessica Alba

What's a newly single star to do in New York City? Step out on the town with her girlfriends, of course!

Sofia Vergara, who recently split with longtime beau Nick Loeb, did just that alongside Jessica Alba and sisters Samantha Ronson and Charlotte Ronson on Thursday.

The celebrity clique partied the night away at the Dream Downtown Hotel's PH-D Rooftop Lounge, arriving around 1 a.m.

The ladies "were all enjoying themselves and taking lots pictures of each other," says an onlooker. "Sofia was relaxed and was all about having fun."

Wearing a long blue bandage dress with platform beige heel and two snake bracelets, Vergara sipped on white wine and danced with Alba. The group mingled until 2:30 a.m.

It's been a busy week for the Modern Family star, who also seemed "in the best mood" at the Einstein College of Medicine's Annual Spirit of Achievement Awards at the Plaza Hotel in New York on Wednesday.

She also looked flawless on the red carpet at the Met Gala on Monday.