"Four choppers left Uganda, one landed in Garissa," said Kenyan army spokesman Bogita Ongeri.
The three other helicopters went missing around the Mount Kenya region, but "the pilot of one has communicated to us," he added.
The helicopters, which took off from Uganda on Sunday, are feared to have crashed in the dense forested foothills of snowcapped Mount Kenya, Africa's second highest peak at 5,199 metres (17,057 feet).
The pilot of the third helicopter had radioed for help from the Mount Kenya region, but rain and poor weather conditions are hampering rescue efforts.
"A search and rescue team has been dispatched," Ongeri added. "As of now we do not know that have crashed.... The terrain and weather are unfavourable."
Uganda last week said it would send combat and transport helicopters to Somalia to support the 17,000-strong African Union force there, who are fighting Al-Qaeda linked Islamist insurgents.
"We have received reports that one plane is within Mount Kenya," said regional police chief Francis Munyambu. "We do not know where exactly it is, there is a general location that has been stated."
keyboard shortcuts: V vote up article J next comment K previous comment