NAIROBI (Reuters) - Four Americans and their Kenyan pilot were killed when their helicopter crashed just after take-off from a remote island in Lake Turkana in northwestern Kenya, officials said on Monday.

The aircraft came down in Central Island National Park at around 8 p.m. on Sunday, Kenya’s National Police Service said on its Twitter feed, killing all on board.

The cause of the crash had yet to be determined.

The U.S. embassy in Kenya listed three of the four dead Americans as Anders Asher Jesiah Burke, Brandon Howe Stapper and Kyle John Forti, adding that it was offering assistance to the families of the deceased.

The Kenya Civil Aviation Authority (KCAA) said two helicopters took off from the island on Sunday night heading for Lobolo Camp on the mainland. Rescuers found the wreckage early on Monday morning, according to Gilbert Kibe, director general of the KCAA.

“Shortly after take-off, unfortunately one of the helicopters, a Bell 505, registration 5YKDL, lost contact and crashed on the island,” Kibe said in a statement.

The crash came less than a month after a light fixed-wing aircraft crashed in western Kenya, killing all five people aboard including three Americans.