A helicopter has crashed in northern Kenya, killing four American tourists and their Kenyan pilot, officials say.

The helicopter reportedly crashed in Central Island National Park on Sunday.

Police said two helicopters had landed on the island's Labolo tented camp on Sunday evening - one flew away safely. The cause of the crash is not known.

Local media say the pilot, Mario Magonga, once worked for the country's deputy president and had extensive training and experience.

He had previously served as a Kenya Defence Forces pilot, but had been working for a private firm, KIDL Helicopters, since March 2017.

The US embassy in Nairobi confirmed the death of four Americans and named three of them as Anders Asher Jesiah Burke, Brandon Howe Stapper and Kyle John Forti.

Mr Forti was a political consultant in Colorado Springs.

The state Senate and House of Representatives held a moment of silence on Monday in honour of Mr Forti, the Colorado Springs Gazette reported.

Mr Burke also lived in San Diego and is listed as the president of a brand incubator on his LinkedIn profile.

Mr Burke and Mr Stapper were close friends, Mr Stapper's family told CBS 8.

"We offer our sincerest condolences to the family and friends of all those killed in the crash. We are providing all appropriate consular assistance to the families of the American citizens," an embassy spokesperson said in a statement to US media.

Richard Onyonka - a relative of the pilot and the area's MP - said Cpt Magonga had been cleared to fly several high profile guests in the past, including former US President Barack Obama.

"[He] was one of the best helicopter pilots that money could buy," Mr Onyonka told Kenya's NTV.

The accident comes just three weeks after a separate plane crash in Kenya which killed five people including three Americans.