An urgent  rescue operation is underway after an American tourist and a local guide were kidnapped from Uganda’s most popular wildlife park by gunmen demanding a US$500,000 ($700,000) ransom.

Kimberley Sue Endecott, 35, and Ugandan driver Jean Paul were halted at gunpoint in their safari vehicle at Queen Elizabeth National Park on Tuesday (local time) and taken in an ambush by four armed men, Ugandan police have revealed.

An elderly couple were among a group of foreign tourists who were abducted in the wildlife park. The kidnappers and their victims  disappeared into the bush before reporting the incident to authorities, local police said on Wednesday.

The kidnappers then used the phone of one of their victims to make a ransom call to police.

Four tourists were “left abandoned and unharmed” and later were taken to safety, according to a statement issued by the Uganda Media Centre.

A manhunt is underway by Ugandan security forces, police and wildlife officers to find the gunmen and rescue the hostages.

Authorities have set up roadblocks and cut off the border between Uganda and the Congo in the area.

📌 PUBLIC NOTICE

Kidnap of Tourists in Queen Elizabeth National Park – @OfwonoOpondo pic.twitter.com/SX5ZhVkkQl

— Uganda Media Centre (@UgandaMediaCent) April 3, 2019

Police said initial indications were that the kidnapping was financially motivated since the group had quickly made a demand using Endecott’s mobile phone.

“We strongly believe this ransom is the reason behind this kidnap,” they said. “The Joint Security teams have cut off all exit areas on the border between Uganda and the DRC in search of the victims.”

The identity of the kidnappers was unclear. The Somali Islamist militant group al Shabaab has carried out attacks in Uganda in the past, but has never kidnapped anyone for ransom there.

The police believe the group may still be in the park, their statement said.

The park, Uganda’s most visited, is located about 400km southwest of the capital Kampala, near the border with the Democratic Republic of Congo, home to many fragmented rebel groups.

“We want to further reassure the public that this is the first of incident of this kind,” police said.

“Those planning to visit the National Park and its surroundings should not be discouraged. Strengthened safety measures have been put in place for both the local residents and visitors.”

The US embassy in Kampala said it would be issuing a statement later.

In 1999, an American couple, four Britons and two New Zealanders were killed along with four Ugandan guides when their group was ambushed by gunmen in Uganda’s Bwindi Impenetrable Forest. Survivors said the killers appeared to be Hutu rebels based in Congo.

-with AAP