An army colonel and eight troops were arrested Thursday for the deaths of as many as eight protesters during a confrontation last week, Guatemala's attorney general said.

Col. Juan Chiroy Sal, the commander of the contingent that fired at protesters, bears the greatest responsibility for the killings, Claudia Paz y Paz told a press conference in the capital.

Chiroy, she said, "had the mission of rendering support to the police, but he didn't coordinate the actions and disobeyed the order the police commander gave to not approach the site of the demonstration."

Hundreds of people mobilized early last Thursday to block the Interamerican highway at six different points in the western province of Totonicapan.

The protest was spurred by President Otto Perez Molina's proposals for constitutional changes, an overhaul of the curriculum for aspiring teachers and a recent hike in electric rates.

Two truckloads of army troops were sent to the spot known as Alaska to assist police trying to clear the highway.

Col. Chiroy brought his troops to within about 500 meters (1,600 feet) of the main concentration of protesters, told them to get out of the trucks and then left them there, the attorney general said Thursday.

"The most grave and serious thing is that he (Chiroy) abandoned the scene and left the army members without command," she said.

Police managed to dispel the protesters without any casualties, Paz y Paz said.

"The information compiled shows that the police told the army not to approach (the protest) because it was not appropriate," she said.

While the AG's office says six protesters were killed - including two shot in the back - and 34 other people injured, peasant organizations insist eight civilians died.

Guatemala's president announced Wednesday that the military will no longer be used to disperse protests.

Perez Molina, a retired army general who was elected on a promise to crack down on crime, said his administration will allow justice to run its course in the Totonicapan case.

Last week's episode was the first instance of army aggression against peasants in Guatemala since the end of the country's 1960-1996 civil war, which left more than 200,000 dead, most of them indigenous people slaughtered by the military and its allies. EFE