Kimberly Sue Endicott lives in Costa Mesa and works as an esthetician there, friends say.
Friends say she had been talking with enthusiasm about her planned trip to Uganda.
Friend and neighbor Pascale Douglas describes hearing the news as like a "punch to the gut."
She also realized she could have ended up on the same tour.
"She had mentioned when I met her one of her big dreams was to go see the gorillas," Douglas recalled. "At the time she asked me if it was something I would consider doing also, but time went by and she ended up going on her trip."
Ugandan security forces are searching for Endicott and a local driver who were abducted in a wildlife park. Their kidnappers demanded a ransom, authorities said Wednesday.
The missing people were taken in an ambush by four gunmen on Tuesday in Queen Elizabeth National Park, a protected area near the porous border with Congo, according to Ugandan police and a government spokesman.
The kidnappers held up a group of foreign tourists at gunpoint, grabbed two of them and disappeared into the bush. Later the kidnappers, using the phone of one of their victims, demanded a ransom of $500,000, said a statement issued by police.
"We strongly believe this ransom is the reason behind the kidnap," the statement said. "Their vehicle was left parked and the kidnappers went away with the key."
The kidnapped American was identified as Endicott, police said.
The four other tourists were "left abandoned and unharmed" and later were taken to safety after reporting the incident to authorities, according to a separate statement from the Uganda Media Centre.
A rescue party of police, military and game rangers has been sent to find the abducted people, that statement said.
Kidnappings in Uganda's protected areas are rare. Queen Elizabeth National Park, in southwest Uganda, is a popular safari destination in this East African country.
The Associated Press contributed to this report.