Mexico City protests mostly peaceful, isolated breakouts of violence reported

MEXICO CITY, Nov. 20 (UPI) -- Update, 3:30 p.m. EST:

A contingent of protesters in eastern Mexico City confronted riot police. The police approached the protesters after they attacked truck driverattempted to make their way to the airport.

The protesters, most of whom had their faces covered, used rocks, molotov cocktails and other objects to build barricades in the streets.

At least two people have been detained and vehicular traffic has been disrupted in that part of the city.

Original story follows:

Thousands of protesters are expected to take part in a mass demonstration Thursday in Mexico City to express their outrage over perceived government impunity.

The planned demonstration was borne out of frustration with the government's delayed and poorly received response to the disappearance of 43 university students in the state of Guerrero in late September. The circumstances of their disappearance revealed complicity between the local government, police and a prominent drug gang.

Frustration with the government has grown amid new scandals, including first lady Angelica Rivera's $7 million private mansion. Earlier this month, the Aristegui Noticias website reported the mansion is registered to Ingenieria Inmobiliaria del Centro whose parent company has a related organization involved in lucrative government contracts awarded by President Enrique Peña Nieto's administration.

Protesters were scheduled to march toward the city's main square, the Zocalo, from three strategic points: The Angel de la Independencia -- a 1910-vintage monument commemorating the country's first 100 years of independence from Spain -- the monument to the Mexican Revolution, and Tlatelolco square. The latter was the site of student protests in 1968 that culminated with at least 40 students killed at the hands of government forces.

The president has reportedly accused some protestors of attempting to "destabilize" the country.

Downtown Mexico City was mostly shut down Thursday morning, with businesses boarding up their storefronts and riot police patrolling the streets. Federal police have also been called in to back up and support city police.

Security forces have focused their attention on the three points of origin for protests, hoping to limit vandalism and prevent rioting.

Protests were also expected in other parts of Mexico and abroad.

While some rioting has become commonplace in Mexico City every Nov. 20, a key date that marks the anniversary of the 1910 revolution, this year's march is widely expected to be especially tense because of the disappearance and likely murder of the 43 students.