SAN JUAN, Puerto Rico — Roughly 500 U.S. drug agents and Puerto Rican police swept through public housing projects at dawn Friday on the island's west coast in what officials described as the largest operation of its kind in the American territory.

Authorities had arrest warrants for 158 people and hoped to seize more than $1 million in property in an attempt to dismantle drug trafficking gangs and reduce crime in Mayaguez during the upcoming Central American and Caribbean Games, said Special Agent Waldo Santiago, a U.S. Drug Enforcement Administration spokesman.

It was not clear how many arrests and seizures had been made. But the special agent in charge of the DEA's Caribbean division, Javier F. Pena, said the operation caught the "most hard-core and violent traffickers terrorizing this part of the island."

The DEA brought agents from throughout the Caribbean to assist Puerto Rican police in making the arrests and searches in a coastal area known as an entry point for cocaine and other drugs from the Dominican Republic, across the Mona Passage.

Many of the arrests targeted drug operations in public housing complexes near schools and sports facilities that will be used at the upcoming games, which feature about 600 athletes from about 33 countries and will bring thousands of visitors to Mayaguez. The games start July 17.

Drug traffickers in Puerto Rico exploit public housing projects, many of them fenced off from surrounding communities, as key distribution points for cocaine and heroin.

Santiago said Puerto Rican police intend to "assume control" of six public housing complexes to help prevent violence during the games.

As a U.S. territory, Puerto Rico is a favored transshipment point for South American drugs bound for the U.S. mainland. Some of the drugs are consumed locally and authorities blame the Caribbean island's soaring homicide rate largely on feuds between rival drug rings.