The Attorney General of the Federal District (PGJDF) reported that 24 youths are still detained at the agency 50 of the Public Ministry accused of various crimes.
Many of those arrested were busted by secret police dressed as civilians.
More than 30,000 people turned out on the streets of Mexico City on Thursday to demand justice for student protesters killed by Mexican security forces in a 1968 demonstration. The killings took place a few days before the Mexican capital hosted the 1968 Olympic Games. The number of deaths in the incident is still disputed and no one has ever been jailed for involvement.
Shouting "October 2 is not forgotten," AFP reports protesters set off from the Square of Three Cultures where the massacre took place and from the capital's Chapultepec park to meet for a rally in the main Zocalo square.
"I'm here to denounce the most despicable act committed in Mexico," Aarceli Bernal, a 26-year-old student, said.
Protesters in Tlatelolco drew chalk figures on the ground covered with blood stains to remember those killed by the security forces.
Newspaper cuttings of the massacre, showing soldiers standing ready to fire, were plastered on a candle-laden altar in one corner of the square.
Felix Hernandez one of those who helped to organize the march said, "Our struggle still lives to know the truth about what happened that October 2nd."
Melissa Toscano Lazcano writes today in the student newspaper at San Antonio College:
"Dos de Octubre; no se olvida" is a historical motto that still resounds in the hearts of Mexicans familiar with the events of 1968. "Second of October; don't forget."
I'm not referring to the Olympic Games set in Mexico City that same year, but of the military shooting of students and civilians resulting in unknown hundreds of wounded, dead and disappeared individuals during a student meeting at Plaza de las Tres Culturas in Mexico's Tlatelolco."
...This happened around my father's early 20s and he recalls the military tanks driving along the Mexican streets intimidating more than watching over their brother citizens days before the fatal climax."
...One may not be directly affected and not care to acknowledge its significance, but it is an important lesson for anyone who values human dignity."
Amnesty International described what happened that day in downtown Mexico City, just days before the 1968 Olympics. Police, military and unidentified armed men surrounded La Plaza de Las Tres Culturas, Tlatelolco, "The square was full of people demonstrating against police brutality as part of a general student strike that followed the beating of students by the anti-riot police "los granaderos" in July. At about 6pm, they opened fire, from armoured vehicles using heavy weapons and soldiers on foot carrying bayonet rifles. They fired on the square packed with students and on surrounding residential buildings."
Cuauhtemoc Padilla Marroquin, a teacher who was 15 when the massacre took place told the LA Times, "I remember how the tanks rolled over the dead and the injured, how they attacked a number of my friends with bayonets."
Javier Zúñiga, now a special advisor at Amnesty International, then a lecturer at the National School of Agriculture, had brought his wife and two-year-old daughter to what was expected to be a peaceful event that October day. They witnessed the arrival of government troops from a nearby bridge overlooking the square.
"Forty years on from the Tlatelolco massacre, so many disturbing questions remain unanswered," said Javier Zúñiga. "Who ordered the massacre? For how long had it been planned? How many were killed? Who are those whose bodies still have not been identified?
Amnesty yesterday called on the Mexican government to finally conduct a real investigation and take appropriate action.
"President Calderón’s government has been all but silent on this dark chapter in Mexico’s history. We challenge this administration to open all relevant archives and records, establish a new and independent inquiry, and lift the obstacles preventing those responsible for this horrific crime being brought to justice."
Natalia Gonzales Servin, 18, commented aptly during the march,
"When I was little and my mother told me what happened [that night], I couldn't believe it," the student said. "How could it be possible that so many people died and the people did nothing and the media less?
"But as I grew up, I realized that a lot of things happen but people don't act -- it's like they're asleep. 1968 was an awakening."
Clashes on '68 massacre anniversary
Protesters clashed with police in Mexico City on Thursday at a commemoration of a student massacre in 1968. Eighteen police officers were injured and 20 people were arrested during the march. Confrontations took place with police as demonstrators demanded justice for those killed in the 1968. When protestors attempted to paint graffiti on a city building wall, police moved in, leading to scuffles.
40th anniversary of the 2 October massacre in which between 44 and 300 student protestors were killed.
The massacre took place ten days before the Mexico Olympic Games of 1968, when security forces opened fire on a crowd of peaceful protestors, then hastily covered up evidence of their actions.
The exact number of victims remains a mystery. Authorities released 44 bodies, but US Central Intelligence Agency reports estimate the number of deaths to be in the hundreds.
Nobody has ever been prosecuted for the massacre.
Political analyst and Mexico specialist Colin Harding was in the country for the first anniversary of the massacre in 1969 and spoke to witnesses.
"People took refuge in the lifts of apartment buildings...the soldiers came along and just sprayed them with bullets,' he told RFI. "It was the most unbelievable event ... Mexicans have never really got over it."
Thursday's protesters set off from the Square of Three Cultures, where the killing took place in 1968, shouting "2 October is not forgotten". Students drew chalk figures covered in blood stains on the ground to represent those killed.
Amnesty International called on Thursday for the government of President Felipe Calderon to establish the truth behind the massacre, saying it was time for the government to assume its responsibility in the matter.
In 2001, President Vicente Fox created the office of the special prosecutor to investigate crimes which took place during Mexico's "dirty war" against left-wing activists, which began in the 1960s and lasted until around 1980.
The Interior Minister at the time of the 1968 massacre was a target of the investigations. Luis Echeverria was in charge of both the federal police and a clandestine military unit at the time of the massacre. He later became President of Mexico.
Mexican courts have blocked attempts to prosecute him for genocide.