Seventeen Colombian military personnel died when their helicopter crashed in rough weather, the army said.
It confirmed the deaths in a statement on Monday, after the MI-17 army helicopter went missing on Sunday in a western central region of the country.
Rescuers "are carrying out procedures to remove the bodies of our military personnel from the scene of the accident," it said.
"I deeply regret what happened," President Juan Manuel Santos said earlier in a speech, as it was looking likely that those on board had been killed.
"The first assessments indicate that the accident could have been linked to the bad weather in the area, but experts will confirm or refute that assumption," Monday's army statement said.
Santos said the victims were providing support for operations against the leftist insurgent group ELN.