An aerial file image taken on June 30, 2018 shows a part of Turkana South Island in Lake Turkana, the world's largest desert lake, in northern Kenya. Getty

Nairobi, Kenya -- Four Americans and a local pilot were killed in Kenya when their helicopter crashed on an island in Lake Turkana in the north, police said Monday. The crash occurred Sunday night in Central Island National Park as two helicopters took off after a visit to the Lobolo tented camp, according to an internal police report seen by The Associated Press.

The U.S. Embassy in Nairobi confirmed to CBS News the deaths of the four Americans but was only able to identify three of the victims; Anders Asher Jesiah Burke, Brandon Howe Stapper and Kyle John Forti.

One helicopter lost contact and crashed soon after takeoff around 8:30 p.m., Kenya's Civil Aviation Authority said in a statement. It said a search and rescue mission found the wreckage shortly after 3 a.m.

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It said an investigation was under way into the cause of the crash.

Lake Turkana is a UNESCO World Heritage Site, and is considered by anthropologists one of the most likely places from which humanity originally evolved, along with the wider Rift Valley area.

Last month two Americans were among five people killed when their plane crashed as they were traveling to Lodwar near Lake Turkana. Kenyan police had reported three Americans killed but the U.S. Embassy confirmed two.

Kenya has a vibrant airline industry, with national airline Kenya Airways operating internationally and locally alongside successful low-cost airlines and many charter companies that fly planes and helicopters.

According to the International Air Transport Association (IATA) in 2014, some 130,000 planes land and take off from Kenya each year, and the country has 35 operating airlines.

The IATA said Kenya's air transport infrastructure quality ranks 6th out of 37 countries surveyed in Africa.