Police say she never made it to a meeting place at 8:30 p.m. The missing girl's mother works the graveyard shift and often sleeps until late afternoon.
Police say there was a long delay from when she was last seen until she was reported missing.
"[We] started activating a lot of personnel to start searching for her," Westminster Police Detective Trevor Materasso said.
Westminster police sent out an emergency text alert advising residents to be on the lookout. An Amber Alert has not been issued.
Ridgeway's neighbor, Sarah Johnston, says she's very concerned about the safety of the missing 10-year-old.
"It's really hard to wonder what could go on," Johnston said. "She is over at our house all the time. just really miss her."