Colombia's armed forces have relieved seven soldiers of their posts for their alleged responsibility for the murder of three children last month.
Action was being taken against the men, including two colonels, for "failures in the command and control of their troops", an army statement said.
A teenage girl was allegedly raped before being killed with her brothers, aged nine and six.
A military spokesman promised full co-operation with investigators.
The armed forces moved quickly to quash any rumours of a cover-up, says the BBC's Jeremy McDermott in Colombia.
"The armed forces are not going to tolerate any human rights violations of any Colombian," said Adm Edgar Cely, head of the armed forces.
The information was painful but was not going to be hidden from the public, he vowed.
The seven men removed from active service are accused of failing to control some 60 men under their command in Arauca, near the Venezuelan border, where the alleged crimes took place.
On 14 October, three children - a girl aged 13 or 14 and her two younger brothers - were killed in the municipality of Tame. The boys are believed to have witnessed the rape of their sister.
Troops were in the area at the time of the alleged murders.
The children's beheaded bodies, showing signs of torture, were found in a common grave, the Spanish news agency Efe reported.
Speaking on Wednesday, the army commander, Gen Alejandro Navas told Colombian media that a sub-lieutenant had confessed to having sexual relations with the murdered girl, but denied any involvement in the killings.
The soldier also told investigators he had had relations with another girl, aged 13, on 2 October.
Gen Navas said investigations were continuing into whether soldiers had any involvement in the murders.