SAN FRANCISCO (CBS SF) – Additional search and rescue personnel have been brought into the search for a 15-year-old Danville girl whose bike was found Tuesday morning near the Golden Gate Bridge, a National Park Service spokesman said.

The Marin County sheriff’s department is adding to the multi-agency intensive search for Danville resident Allison “Alliy” Bayliss, 15, who was last seen on Monday at 8 a.m. on her bike in front on San Ramon Valley High School in Danville, National Park Service spokesman Howard Levitt said.

After discussions with Allison’s family, Danville Police Chief Steve Simpkins said Allison is considered at-risk and that the case is “absolutely not criminal, it’s a personal matter.”

About 100 volunteers have arrived at the Presidio in San Francisco since Tuesday morning after Allison’s parents called authorities when they found her bike parked in the Battery East parking lot near the Golden Gate Bridge’s San Francisco side, Levitt said.

Simpkins said the Danville volunteer support in Allison’s search has been awe-inspiring.

“The community of Danville is acting as if it’s their own family member,” Simpkins said.

Searchers are covering shorelines and nearby waters, and some volunteers are planning to expand the search deeper into San Francisco, away from the coast, Levitt said.

Plans have not been determined for a night search, Levitt said.

Once it is dark, authorities have to start worrying about the safety of the searchers, said Simpkins, who has been in San Francisco helping with the search since Tuesday morning.

Authorities and family members are waiting in Danville should Allison return home at any point, Simpkins added.

A Facebook event page, “Find Alliy Bayliss,” has been created with more than 10,000 people “attending” the search. One posting on the event’s wall includes a missing-persons flier. The flier says Allison left a suicide note at her home.

A vigil is planned for Allison at 7 p.m. Wednesday at the Danville Congregational Church at 989 San Ramon Valley Blvd. in Danville, church office manager Lynda Manstrom said.

Some of the congregation’s youth group members are friends with Allison and are concerned about her, Manstrom said.

Allison is described as a white girl with blond hair who is 5 feet 8 inches tall and weighs 130 pounds. She was last seen wearing a red zippered hooded sweatshirt and blue jeans.

Levitt said anyone with tips or information should call the Danville police department at (925) 646-2441.

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