Mexico City, Mexico (CNN) -- Eight of nine police officers from Mexico's Guerrero state who disappeared after an attack have been found dead, state media reported.
A ninth officer was injured but survived the attack, which occurred when the officers were investigating a death Friday evening, the state-run news agency Notimex said Saturday.
A group of armed attackers intercepted the officers in northern Guerrero Friday, the state attorney general's office said in a statement late Saturday, according to Notimex.
State prosecutors have opened a homicide investigation to find the people responsible for the police officers' deaths, the statement said.
Six of the officers were found dead in a pickup truck on a highway Saturday. Their bodies had been mutilated, the prosecutors' statement said.
Two other officers from the group were found dead in the neighboring state of Mexico earlier Saturday, police said, according to Notimex. The official vehicle in which they had been traveling to investigate the death was found nearby.
The officers were attacked by 30 armed individuals, the agency said.