ORANGE PARK, Fla. -- More than 100 law enforcement officers, twice that many U.S. Navy personnel, and a team of mounted search-and-rescue volunteers searched every inch of northern Clay County Wednesday, looking for a 7-year-old girl who vanished without a trace Monday afternoon while walking home from school.

The mother of Somer Thompson spoke to the media for the first time Wednesday, pleading for help bringing the girl home.

"Just drop her off somewhere," Diena Thompson said through her tears. "I don't care if you ever get in trouble -- I want my baby back."

Investigators said they have hundreds of leads but no clues nearly three days after Somer vanished while walking in her Orange Park neighborhood.

"We're still at a situation where Somer has disappeared off the face of the earth," Clay County Sheriff Rick Beseler said.

Beseler joined Somer's mother in appearances all three national network morning news shows Wednesday as well as speaking to the local media.

"Somer, you're not in trouble -- if you're scared, just come home," Diena Thompson said directly to her daughter. "If somebody has her, please, please bring her back to us. She belongs with her family."

"We just really need a break in this case. We need a tip, we need a phone call," Beseler said. "Somebody knows where Somer is, and we need that person to call us."

Somer is described as 3 feet 5 inches tall and 65 pounds with brown hair in a ponytail with a red bow. She was last seen wearing a cranberry-colored sweatsuit with pink stripes on the sleeve and pants. She also had a black, pink and white backpack with a skull and hearts. She may be wearing a white hat and scarf.

Her mother described a large, irregular shaped birthmark on Somer's left shin as an additional distinguishing feature.

Wednesday Developments

Nearly 200 sailors from Naval Air Station Jacksonville joined the search efforts Wednesday morning, covering wooded areas and the grounds of a wastewater treatment plant less than one mile from where Somer disappeared.

Texas Equusearch, a volunteer mounted search-and-rescue team that was involved in searching for Haleigh Cummings in Putnam County and Caylee Anthony in Orange County was to arrive in Orange Park on Wednesday afternoon.

Channel 4 learned that a search was conducted at two landfills where Clay County's garbage is dumped. Clay County officials said the search of the Rosemary Landfill in Green Cove Springs and one in Folkston, Ga., were routine -- not the result of a tip -- and nothing related to this case was found.

The Justice Coalition on Wednesday offered a $25,000 reward for Somer's safe return and Florida Gov. Charlie Crist is expected to visit the search command post in the afternoon.

Beseler also said Wednesday morning that investigators have located a vehicle and person involved in a possible child-abduction attempt in Orange Park 10 days earlier and said there is no connection between that incident and Somer's disappearance.

Investigators Baffled

Somer vanished on her mile-long walk home from Grove Park Elementary School in Orange Park.

Diena Thompson told detectives that Somer was squabbling with another child, and her sister told her to stop. The girl got upset, ran ahead of the group and wasn't seen again.

While investigators said they have no evidence someone took Somer, they said her age and the length of time that she has been missing make them very concerned for her welfare.

"She is definitely endangered and we do suspect foul play," Clay County Sheriff's Office Sgt. Dan Mahla said at a Tuesday afternoon briefing.

Beseler said investigators are baffled. He said officers have expanded the initial search area and interviewed about 75 known sex offenders in a five-square-mile radius. Teams of volunteers are walking arm-to-arm through the woods, and deputies are using helicopters and search dogs.

Hundreds of law enforcement personnel with the support of helicopters, bloodhounds, dive teams have searched the neighborhood and nearby woods since Monday night.

FBI has also assigned a member to assist Clay County, along with staff from the Florida Department of Law Enforcement.

An Amber Alert was issued at 9 a.m. Tuesday. Beseler estimates that more than 10,000 flyers with Somer's picture were distributed across northeast Florida by Tuesday night.

After appearing on network news shows, Beseler expects they will begin getting tips from around the country.