Christian Estrosi, mayor of Nice, presents Knox Leon's birth certificate
Eliot Press/ Bauer-Griffin
They're here, officially: On Sunday, Mayor Christian Estrosi of Nice, France, presented one of the birth certificates of Angelina Jolie
and Brad Pitt
's twins on the steps of Nice's Fondation Lenval hospital, where son Knox Leon and daughter Vivienne Marcheline were born Saturday.
The typed certificate revealed that Knox was born at 6:27 p.m. on July 12. Sister Vivienne came within a minute of that time, Dr. Michel Sussmann tells PEOPLE.
The document also showed the Mayor's signature, as well as Pitt's initials, the letters WBP representing his full name, William Bradley Pitt.
The mayor entered the hospital at 3:24 p.m. to oversee the signing, telling PEOPLE, "It's a pride to Nice and all its citizens."
Knox is the 3,702 registered birth certificate in Nice for 2008.
In welcoming the twins, Estrosi told reporters, "On behalf of the inhabitants of Nice, I congratulate the happy parents, the most famous couple of the world who have chosen our city for this happy event."
Earlier in the afternoon, a large bouquet of white roses and lilies for Jolie were delivered.
Estrosi added: "I also congratulate the four brothers and sister of the newborns who are [history won't forget it] real 'Niçois' ('citizens of Nice')."
More on this story
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The Jolie-Pitts Welcome a Son & Daughter
PHOTOS: The Scene: A 'Nice' Arrival for the Twins