Police in Colombia’s capital Bogota arrested approximately 70 protesters Tuesday for carrying dangerous items at this year’s annual Labor Day marches.

The accused were taken to the Permanent Justice Unit for allegedly carrying knives, aerosol cans, and stones.

The Bogota Police Department mobilized 5,000 troops in an attempt to prevent the amount of damage caused in years past. Last year, more than 20 shopping centers in the capital were damaged by home made explosives and police resorted to using tear gas on violent and peaceful protesters.

Nationally, authorities deployed some 35,000 security forces personnel. Police were reportedly particularly worried this year due to the recently passed Free Trade Agreement with the United States which has angered many labor groups in the country.

Police told local media that only one person had been injured in the Bogota marches and that a home made bomb damaged three shops.

According to the police’s official report, 30 of the arrested protesters had already been released, including six minors.

Disturbances were also reported in Medellin and protesters, many of them members of the Confederation of Workers, were sprayed with tear gas.

Arrests and violence have only been reported in the capital and in Medellin, but marches were also held today in Cali, Barranquilla, Villavicencio, Ibague, Bucaramanga and Cucuta, among other cities.

From Colombia Reports