My cousin helped clarify, it was a petard style firework, picked up by accident with the garbage, which went off when thrown in the truck, injuring the sanitation worker. There have been raucous celebrations for the feast days of San Juan. Even as the government has been negotiaing with the FARC to end hostilities. It’s always difficult to know what to imagine. The spanish version of wikipedia is helpful in understanding the use of petards in contemporary spectacle throughout the spanish speaking world. The english version focuses on the historical use as a seige wall breaker. I feel for the family of the injured city employee.

Un petardo es un tipo de fuego pirotécnico, usualmente un tubo de un material poco resistente, generalmente de papel o de cartón, que se rellena con pólvora o con otro explosivo y que se cierra dejando libre una mecha. Al prenderle fuego, se produce una detonación que varía en potencia y efecto luminoso en función del relleno.