Guatemala has arrested an army colonel and eight soldiers accused of killing indigenous demonstrators during a protest last week.
Col Juan Chiroy Sal and the troops were charged with extrajudicial killing.
Prosecutors say they opened fire, killing six demonstrators who had blocked a motorway during a protest over electricity prices in Totonicapan, west of the capital.
Guatemalan President Otto Perez Molina initially denied military involvement.
At a news conference last week, he said unidentified people had shot the demonstrators - most of them indigenous Guatemalan - from the back of a lorry with a civilian licence plate.
But investigators had found more than 100 shells at the scene from a type of ammunition used exclusively by the military, prosecutor Claudia Paz y Paz said.
Col Chiroy "abandoned his troops and left the security forces without command," she said.
President Molina has since declared that the army would no longer be deployed at civilian protests.
"The most sacred right we have, the right to live, has been violated," he said.
The colonel and the eight soldiers appeared before a judge in Guatemala City on Thursday and were told to remain in jail. They will appear in court on Friday.
Six people were killed and more than 30 were wounded during the clashes.
It took place on 4 October on a stretch of the Pan-American Highway some 170km (105 miles) west of Guatemala City.
The demonstrators were angry at constitutional reforms which the government says will modernise Guatemala's economic and regulatory systems.
But protesters say the changes will raise electricity prices.