Mariska Hargitay and daughter Amaya Josephine
04/07/2011 AT 11:00 AM EDT
04/06/2011 AT 08:00 PM EDT
Mariska Hargitay has a big surprise to share.
The Law & Order: SVU star
and her husband, actor Peter Hermann, have adopted a baby girl, she tells PEOPLE exclusively.
Baby Amaya Josephine was born about a week ago and is from the United States.
"I'm deliriously happy," Hargitay, 47, tells PEOPLE. "From the minute she was born, she was just surprisingly alert and so full of love."
"We were considering both international and domestic adoption and we're thrilled that this is the way our prayers were answered," she adds. "We talked a lot about mixed-race adoptions, and we are very excited that we are now a multi-racial family. We're just so happy she's here."
And there's one family member who's more excited than anyone: Hargitay's 4½-year-old son, August
"He is over the moon," says the actress. "He calls her his baby because he says the whole thing was his idea. He always talks about how he's going to protect her. He's going to be a great big brother."