Kazakhstan President Nursultan Nazarbayev blamed an "act of terror" for the deaths of 15 people, found at an outpost near the border with China.
The bodies of 14 Kazakh border guards and a civilian were found at the burnt-out border post outside Almaty over the past two days.
President Nazarbayev said it was "likely it happened as a result of internal conflicts".
But he gave no further details about who he thought might be responsible.
"When such incidents take place in peace time it requires very thorough investigation," he added.
The comments represent the first clear indication that the authorities believe the deaths were the result of foul play rather than an accident.
Initially the bodies of 12 border guards were found along with a park ranger, but it later transpired that another two guards had also died at the border post in the Tian Shan mountain range in the east of the country.
The cause of death is still not known and it is unclear whether the victims died in the fire or were killed beforehand.
One more person, also believed to be serving at the outpost, has still not been located according to the Associated Press news agency.
Kazakhstan has been seen as one of Central Asia's most stable states, but over the past year there have been a handful of bomb attacks, which have been blamed on Islamist militants.
However there is no evidence to suggest they are responsible for these deaths.