Eleven people, most of them foreign tourists, died early Tuesday when a plane crashed in Kenya’s coastal Kwale region as it traveled toward the Maasai Mara National Reserve.

According to a statement from Mombasa Air Safari, the victims included eight Hungarian nationals, two Germans, and the Kenyan pilot. Authorities reported that the aircraft went down in a forested, hilly area roughly 40 kilometers (25 miles) from the Diani airstrip.

Kwale County Commissioner Stephen Orinde told The Associated Press that the crash occurred at 05:30 a.m. local time amid heavy rainfall in the coastal region. Investigators have launched a probe to determine what caused the accident.

The airline did not specify the plane’s exact departure time from Diani airstrip, explaining that “the pilot failed to communicate upon departure” and that air traffic controllers “tried to reach him for 30 minutes before the plane was located.”

Officials said the impact caused the aircraft to burst into flames, leaving only a charred wreckage. Witnesses told the AP they heard a loud explosion and, upon arriving at the crash site, discovered human remains that were “unrecognizable.”