President Yoweri Museveni vowed on Wednesday that Ugandan forces would track down those responsible for the deaths of a safari guide and two foreign tourists who were honeymooning in a national park.

Ugandan authorities have accused the Allied Democratic Forces (ADF) of killing the couple, a South African and a British national, and their Ugandan guide on Tuesday evening near the Queen Elizabeth National Park.

The ADF, which began as an uprising in Uganda but has been based in the nearby Democratic Republic of Congo since the late 1990s, pledged allegiance to Islamic State four years ago.

Islamic State claimed responsibility for the attack, its telegram channel said.

After operating primarily in Congo for years, ADF has stepped up attacks inside Uganda in recent months, including a raid in June on a secondary school that killed more than 40 people.

“It was a cowardly act on the part of the terrorists attacking innocent civilians and tragic for the couple who were newlyweds and visiting Uganda on their honeymoon,” Museveni said in a post on the social media site X, formerly Twitter.

“Of course, these terrorists will pay with their own wretched lives.”

Uganda and Congo launched a joint ground and air operation against the ADF in December 2021 in an effort to eliminate them from eastern Congo.

Uganda says it has succeeded in killing more than 560 fighters and destroyed their camps, but Museveni on Wednesday acknowledged “gaps” in how the security services had dealt with “remnants” of the group that continue to pose a threat.

The Bridgeway Foundation, a U.S.-based think tank that studies the ADF, noted in a brief analysis that the attack occurred about 20 km (12 miles) from the Congo border, far deeper into Ugandan territory than previous raids.

Britain’s Foreign, Commonwealth & Development Office on Wednesday advised against all but essential travel to Queen Elizabeth National Park.

The office said it was providing consular assistance to the British national’s family.