WESTMINSTER, Colo. (AP) -- Police say they're using a new team of search dogs Sunday as they scour a Denver suburb for a missing 10-year-old schoolgirl.

Westminster investigator Cheri Spottke says more than 800 volunteers helped look for Jessica Ridgeway Saturday.

She was last seen Friday morning walking to a park where she normally meets classmates and they walk to school. But police say she didn't make it to the park or school. The search began later Friday after an Amber Alert was issued.

Spottke says teams of 50 searchers covered numerous areas of town on foot Saturday.

Jessica weighs 80 pounds and is 4-feet-10 with blue eyes and blond shoulder-length hair. She was wearing a black jacket.

Authorities are monitoring social media sites and following up on more than 100 tips.