Tennis star Serena Williams has gone into labor at St. Mary's Medical Center in West Palm Beach.

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According to sources from WPEC, Williams checked in to the hospital on Wednesday and doctors induced labor on Thursday night.

READ: What were they like? Coach recalls Venus, Serena's youth in Delray 

The entire first floor of the hospital has been cleared to give Williams privacy, and no one is allowed inside without security clearance, WPEC reports.

The 35-year-old is engaged to Reddit co-founder Alexis Ohanian. She announced her pregnancy in April through a Snapchat. This will be her first child.

The sex of the baby is unknown, but Ohanian revealed to Vogue that he believes their child will be a girl.

Williams threw a baby shower at Nick's 50's Diner in West Palm Beach on Aug. 4. Celebrities Venus Williams, Eva Longoria, Ciara and Lala Anthony were in attendance, along with 75 of Serena's closest friends.

Serena and Venus Williams moved to Delray Beach in 1991 with their father to train at the Delray Beach Tennis Center. The sisters recently made their primary residence at the BallenIsles Country Club in Palm Beach Gardens.