Police were combing a wildlife park in Uganda on Thursday as they searched for an American tourist who was kidnapped at gunpoint.

The 35-year-old U.S. woman and her local driver were abducted when a safari group was ambushed in Queen Elizabeth National Park, which borders the Democratic Republic of Congo.

The assailants have demanded $500,000 for their release.

Authorities said the victims are believed to still be in Uganda.

Miha Logar, a tourism operator who has worked in the region for nearly two decades, said security at the border has been heightened in recent months due to an Ebola outbreak in neighboring Congo.

"Any official border crossing actually has special teams that are really paying attention to each and every individual crossing the border," he told NBC News.

Local official Nelson Natukunda said that the army and police were using both ground troops and aircraft to search 1,200 square miles, an area larger than Rhode Island.

"They have only concentrated the search in the game park,” Natukunda said.

Natukunda added that there was another kidnapping in the park last month and the victims were taken to Congo but released after a ransom was paid. The victims of the previous incident were locals, authorities said.

Queen Elizabeth National Park is located in southwestern Uganda. Martin Zwick / UIG via Getty Images file

The identities and affiliations of the kidnappers are unknown and police have previously said they believe the ransom is the motive behind the incident.

Four others in the tour group escaped the incident unharmed, according to the government.

"Right now we don't know the exact location where she is, but the security is doing its work," said Bashir Hangi, the communications manager for the Uganda Wildlife Authority, referring to the American.

The U.S. Embassy in Kampala confirmed it was aware of the kidnapping and warned travelers in the area should be cautious due to the ongoing security operation.

Despite the kidnapping being characterized as rare by local officials, Logar said the tourism industry will likely take a hit beyond Uganda.

“When something happens, not just in a specific area of a specific country, if something happens in Africa, people get scared travelling to Africa. That’s how the geographical perception of this continent is,” he said. "People are held at gunpoint in America as well."