Though some of Mexico's plushest resorts, such as Acapulco, are located in Guerrero, it is a poor agricultural state marked by rural protest.
In a stinging indictment of the Guerrero state government, the commission accused high-ranking officials of trying to cover up the massacre and urged the governor who was appointed by the ruling party, Ruben Figueroa, to dismiss and investigate them.
Speaking to reporters, Mr Figueroa said he would fully accept the commission's recommendations. All the cabinet changes called for would be carried out, he added.
In its report, the commission said police "executed" at least one of the peasants stopped at a roadblock on 28 June near the town of Coyuca de Benitez, 275 miles south-west of Mexico City. It said that at least three other victims were shot at close range.
"Of the 17 dead peasants, at least one, Mr Daniel Lopez Castaneda, was summarily executed," said Jorge Madrazo, the commission's president. "The police fired indiscriminately [at the peasants]."
He expressed doubts that the peasants, members of the left-wing Peasant Organisation of the Southern Sierra, opened fire in the encounter, as Mr Figueroa has alleged.