The savage execution of innocent Bronx teen Lesandro Guzman-Feliz shocked the city — but for the bloodthirsty Trinitarios street gang, it was business as usual.

The primarily Dominican gang was born out of the violence of Rikers Island, founded behind its bars in 1992 by three inmates, including convicted murderer Leonides “Junito” Sierra, according to a Department of Justice profile of the group.

Ever since, the murderous mob, which is concentrated in the Bronx and upper Manhattan, has plagued the city’s streets as the country’s largest Dominican gang.

Like their fiercest rivals, a crew called Dominicans Don’t Play, the Trinitarios recruit heavily in the hardscrabble hallways of city public high schools, and maintain a young membership, averaging in the teens or early 20s, police sources said.

As the two gangs battle for turf to peddle heroin and cocaine, bloody brawls between them have claimed the lives of at least 10 people since 2005 and injured several more, according to the Department of Justice.

The Trinitarios’ name is reportedly an homage to three Dominican revolutionaries.

Their weapons of choice include machetes.

Guzman-Feliz, 15, was attacked outside a Bronx deli and hacked to death with a machete and knives by a group of suspected Trinitarios who may have mistaken him for a similar-looking youth who had made a sex tape with a relative of one of the thugs.