MEXICO CITY (AP) — Prosecutors in southern Mexico said Tuesday they found an AK-47 assault rifle, hand grenades and gasoline bombs at the scene of a protest where a violent clash between student demonstrators and police resulted in the death of two students.
Alberto Lopez, the attorney general of the southern state of Guerrero, told a local radio station he believed "there were outside elements involved in the protest" who were not students at the rural teachers college where the protest originated.
Late Monday, Lopez said at a news conference that eight hand grenades had been found at the scene of the demonstration on a highway in the state capital, Chilpancingo.
Hours after Lopez's news conference, Guerrero Gov. Angel Aguirre told Radio Formula he had fired him and the chief of the state police "to facilitate the investigation."
The federal Attorney General's Office said it was opening an investigation into the students' deaths.
The highway leads to the Pacific coast resort of Acapulco, and the students had allegedly hijacked buses and blocked the road to press their demands for more funding and assured jobs once they graduated.
Lopez said the students had also set fire to pumps at a gas station on the highway when federal and state police moved in to quell the protest, and that a gas station employee had suffered serious burns in the attack.
His office has said police were using tear gas to repel the demonstrators when shots rang out, and that authorities are still investigating who fired those shots.
Lopez said shell casings recovered at the scene were from an AK-47, a weapon which, like the grenades, are commonly used by Mexican drug gangs but not issued to law enforcement agencies in Mexico.
The students' bodies are still being examined to determine what weapon killed them.
He said students at the Ayotzinapa teachers college had often demonstrated in the past, but that Monday's protest was 'very unusual" in its level of violent behavior.
But at an impromptu news conference in Chilpancingo, students from the college said none of the estimated 300 to 400 protesters was armed. They accused authorities of planting weapons at the scene to justify the killing of the demonstrators.
They said a third student had been seriously wounded and was undergoing surgery.
A coalition of human rights groups issued a statement Tuesday calling the police actions "excessive" and "an irrational use of force." They also claimed that about 40 protesters were missing and about two dozen had been detained by police.
Lopez said many of those detained had been released, and the students said they believed some of their colleagues were hiding in the hills surrounding the highway.
Mexico's public rural teachers colleges, some founded in the 1930s with a socialist philosophy, have long been a hotbed of radical activism. Protest leaders said the students were demonstrating to get funding for a larger incoming class, better conditions at the school and assured jobs for graduates. Recent educational reforms in Mexico now assign most new hiring for teachers' jobs based on competitive tests.
The deaths stirred up memories of Guerrero state's long and tragic history of killings of opposition activists and protesters. Authorities in past administrations sometimes tried to cover up such killings by planting weapons or altering crime scenes.