Blue Ivy Carter - Beyonce and Jay-Z have a Baby Girl!

Beyonce and Jay-Z welcomed their first child Saturday night in New York - a baby girl name Blue Ivy Carter, the little one's arrival coming via scheduled C-section, multiple sources confirm to E! News.

Rihanna gave a warm welcome, tweeting: "Welcome to the world princess Carter! Love Aunty Rih."

Friend and music mogul Russell Simmons was among the first to celebrate the arrival, tweeting the new parents: "congrats to my good friends Beyonce and Jay-Z."

Tyrese Gibson welcomed Blue Ivy Carter, tweeting: "Congrats to you both.. You are loved! Beyonce and Jay are new proud parents of a healthy baby girl.. Blessings!!"