Nairobi, Kenya (CNN) -- Rescue teams searched Tuesday for seven people thought to have survived after three military helicopters came down on the side of Kenya's highest mountain, in a remote area that is home to leopards and rhinoceros.
Two of the helicopters crashed and the third crash-landed on Mount Kenya Sunday as they were on their way to join a peacekeeping mission in Somalia.
Lt. Gen. Edward Katumba Wamala, Uganda's commander of army land forces, said Tuesday that 21 people had been accounted for and the search continues for seven more.
One of the aircraft could be seen burned out on the side of Mount Kenya, said Gen. J.J. Odongo, Uganda's defense minister. However, the military can neither confirm nor deny any deaths at the moment, he said.
The passengers in the helicopter which crash-landed were found and rescued Monday after the pilot issued a distress call.
Kenyan military officer Brig. Francis Ogola said the sites where the other two helicopters crashed have now been found and that military and police aircraft are carrying out a search for the presumed survivors.
"The fate of the occupants remains unknown," Ogola said. However, the team at one of the sites found "no dead bodies," but rather "items ... arranged in a matter that suggest that they have evacuated from that location and they are somewhere in the mountain."
This is cause for "good hope" that the soldiers and airmen will be found, Ogola said.
Conditions on the mountainside may be tough, however.
The survivors will have to contend with rugged terrain and altitude. Mount Kenya is the second-highest peak on the African continent, after Kilimanjaro, at just over 17,000 feet, according to UNESCO.
According to the Mount Kenya park service and UNESCO, elephants, rhinos, giant forest hogs and leopards are among the creatures that live in the area. The mountain sides are riven by steep valleys and the vegetation is alpine higher up, changing to bamboo further down the slopes, UNESCO says.
Odongo said the crashes were an "accident" and that the helicopters were in "good condition."
Ugandan President Yoweri Museveni has appointed a panel to investigate the cause of the accidents, which will be headed by the president's younger brother, Gen. Caleb Akandwanaho, Odongo said.
However, Odongo said the cause was turbulence due to "bad weather."
Only one helicopter in the group of four made it to their next scheduled stop in Garissa, Kenya, where they were due to refuel.
The helicopters were part of the first deployment of air support for the African Union Mission in Somalia in Mogadishu, where Ugandan, Burundian and other African Union forces are fighting Al-Shabaab, an al Qaeda-linked group.
Odongo said the Ugandan government and army would reassess their capacity to continue with the deployment of military air power to AMISOM following the crashes.
It had taken Uganda more than three months to prepare for the deployment, he added, with all crew undergoing U.N. training.
The aircraft left Nanyuki, in Kenya's Rift Valley, after originally being dispatched last week from Entebbe, Uganda.
Ugandan army spokesman Col. Felix Kulayigye said that one helicopter pilot then made a distress call saying he had made an emergency landing in the mountains.
The pilot and crew of that helicopter were rescued and have been taken safely to Nanyuki Air Force Base, he said.
Al-Shabaab, which has battled Somalia's weak transitional government since 2007, controls much of southern Somalia and is active around the capital city of Mogadishu. The United States listed it as a terror organization in 2008.
Al-Shabaab claimed responsibility for suicide bombings that killed more than 70 people in Uganda in 2010 and has threatened attacks against U.S., Kenyan and Burundian interests in the region.
Journalist Gregory Branch contributed to this report from Kampala, Uganda.