Hundreds of volunteers showed up in Morgan Hill Tuesday to lend a hand in the ongoing search for 15-year-old Sierra LaMar, who went missing a week and a half ago.

The KlaasKids Foundation, an organization that provides search-and-rescue services for families of missing people, was on hand at Burnett Elementary School to manage the search.

By 9 a.m., more than 200 people had registered to help look for Sierra and provide administrative support for the effort, KlaasKids founder Mark Klaas said.

Klaas' 12-year-old daughter Polly Klaas was kidnapped from her Petaluma home in 1993. Searchers looked for Polly for about two months before police arrested a suspect in the case, Richard Allen Davis, who led them to her body. Davis was later convicted of her murder.

Volunteers stood in a long line that wound around Dougherty Avenue as they waited to be checked in at the school.

"This is an amazing turnout," Klaas said, glancing around the school's multipurpose room, which was converted into a makeshift command center.

"We're lucky if we get this many people during an entire search," he said.

KlaasKids, which in 2011 alone provided search-and-rescue services in more than 200 missing persons cases nationwide, was summoned by Sierra's parents last week to assist in their case, Klaas said.

"They asked us if we would help them find their daughter," he said.

Klaas said three search-and-rescue experts flew in from Florida and Texas over the weekend to help prep for the search efforts. KlaasKids is teaming up with similar organizations, including Bay Area Missing and the Laura Recovery Center, for the Sierra LaMar case.

One Bay Area Missing volunteer who turned out in Morgan Hill was Michael Le, whose sister, nursing student Michelle Le,disappeared from Kaiser Permanente Medical Center in Hayward last May.

Her body was found in a remote area between Pleasanton and Sunol in September, and a former high school classmate and friend has been charged with her murder.

KlaasKids helped in the search for Le, which included hundreds of volunteers.

"I wanted to do something to pay it forward and be able to do the same for another missing person's family the way they helped us," Michael Le said.

Volunteers, who were required to be at least 18 years old, were processed in the multipurpose room and some were given orange vests. They were organized into teams of about 15 people before heading out to scour the area.

Sierra LaMar left home for school the morning of March 16 but never showed up to class.

Investigators later found her phone and her Juicy-brand purse containing a neatly folded pair of pants and a T-shirt belonging to the teen. The phone and purse were found separately about two blocks apart along Santa Teresa Boulevard, less than two miles from Sierra's mother's home.

The disappearance is being investigated by the Santa Clara County Sheriff's Office, and is considered simply a missing-persons case since there is still no evidence that she either ran away or was abducted, investigators have said.