Aztec drummers and dancers perform in Tlatelolco plaza where wreaths have been laid in commemoration of the 1968 massacre of student protesters by army troops 50 years ago, in Mexico City, Tuesday, Oct. 2, 2018. Students and surviving leaders of the
Aztec drummers and dancers perform in Tlatelolco plaza where wreaths have been laid in commemoration of the 1968 massacre of student protesters by army troops 50 years ago, in Mexico City, Tuesday, Oct. 2, 2018. Students and surviving leaders of the

MEXICO CITY - Authorities have raised a giant, iconic Mexican flag to half-mast in Mexico City's main square in commemoration of the 1968 massacre of student protesters by army troops 50 years ago.

Students and surviving leaders of the 1968 student democracy movement are planning marches Tuesday to mark the anniversary of an event that caused such revulsion it helped spur long-term political reforms.
 

Mexico's President-elect Andres Manuel Lopez Obrad
Mexico's President-elect Andres Manuel Lopez Obrador arrives to a rally commemorating the 50th anniversary of a bloody reprisal against students, at the Tlatelolco Plaza in Mexico City, Saturday, Sept. 29, 2018. Lopez Obrador vowed Saturday to never use military force against civilians. Troops fired on a peaceful demonstration at the plaza on Oct. 2, 1968, killing as many as 300 people at a time when leftist student movements were taking root throughout Latin America.

It is unclear how many died in the nearby Tlatelolco plaza. Estimates range from the official version of 25 dead to a more recent investigation that identified 44. Activists at the time claimed hundreds, saying large numbers of bodies were carted off in garbage trucks.
 
The government at the time feared the students might try to disrupt the Olympic games held in Mexico City a few weeks later.