Updated

More than 200 volunteers reportedly gathered Saturday in Colorado to help police search for a missing 10-year-old girl.

Jessica Ridgeway was last seen walking to Witt Elementary School in Westminster, Colo. Ridgeway normally meets a friend at Chelsea Park on her way to school, but she didn't make it to the park or the school on Friday.

Police say they got a late start looking searching because her mother didn't immediately realize she was missing. Officers say the woman works nights and slept through calls from school officials to tell her Jessica hadn't arrived.

An Amber Alert was issued late Friday.

Police mounted an overnight search for Ridgeway Friday involving some 50 personnel as well as members of the public, family and friends. Police say a bloodhound and thermal equipment were being used.

"Police have conducted area searches of the trails, parks and open spaces in the surrounding area. Officers have also made door to door contact and notified approximately 12,775 residents by telephone," Westminster police told Fox 31 Denver.

A new team started search early Saturday morning, according to police spokeswoman Cheri Spotke.

More than 200 people joined the search Saturday, splitting up into small groups and leaving on buses to conduct their search for Ridgeway, Fox 31 Denver reports.

Authorities cited a child custody dispute involving her father, but said they don't believe Jessica is with him.

Click for more from Fox 31 Denver.

The Associated Press contributed to this report.