Police officers found the girl inside Life Span daycare around 8 p.m. Thursday, The Palm Beach Post reported.
Rose Anne Brown, a spokeswoman for the city, said the child's father went to the daycare around 5:45 p.m. and discovered the gates were locked. He then went home and found no one else had picked her up.
Family members, whose names were not reported, notified police who went to Life Span where they saw the girl through a window, standing inside the center.
The girl seemed to be safe and in good health but was taken to a hospital in West Palm Beach as a precaution, Brown said.
The Florida Department of Children and Families is expected to investigate the incident and the city will also conduct an investigation, Brown said.
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