The FBI joined the search Tuesday for a 30-year-old California woman believed to have been kidnapped for ransom, authorities said. 

The Vallejo Police Department said Denise Huskins was "forcibly taken against her will" from a home in Vallejo Monday morning, according to a witness who contacted them.

The woman's white 2000 Toyota Camry with license plate 4GQA436 was also taken and eventually found at an undisclosed location.

"We are treating this matter as a kidnap for ransom," Lt. Kenny Park of the Vallejo Police Department told reporters during a press conference Tuesday.

Officers were notified by a 30-year-old unidentified man that Huskins was abducted early Monday morning from Mare Island in Vallejo, about 23 miles northeast of San Francisco, according to Park. The man, however, did not call police until 1:55 p.m., Park said.

Park did not say why authorities believe a ransom may be involved in the case. He said the man who reported the kidnapping witnessed it at the home, but Park did not comment on his relationship to Huskins. 

When asked why the man did not report the alleged kidnapping until hours later, Park said, "that's unknown" -- though he said the man is not considered a person of interest.

"We are currently working with him to piece the puzzle together," he said

Park also said he had no reason to believe Huskins' alleged abduction was connected to recent reports of a peeping tom in the neighborhood.

A massive search is underway in the area, with police seen scouring a nearby marshland and abandoned warehouses, according to Fox affiliate KTVU. 

According to her Facebook page, Huskins is employed as a physical therapist at Kaiser Permanente Medical Center in Vallejo and previously worked at a Southern California orthopedic institute.

Huskins is described as 5-foot-7, weighing 150 pounds, with blonde hair and blues eyes. 

Anyone with information on her whereabouts it urged to call the Vallejo Police Department at 707-648-4524.

FoxNews.com's Cristina Corbin contributed to this report.