CENTRAL ISLIP, N.Y. (AP) — It was a trap, executed imperfectly but with bloody results.

Prosecutors said in a recent court filing that four young men found slaughtered in a Long Island park last April were lured to the site by two female associates of the MS-13 street gang, which was hunting for rivals and perceived enemies.

Once there, the youths — some still in high school — were surrounded by more than a dozen gang members who attacked them with machetes, knives and wooden clubs "in a horrific frenzy of violence," according to the court papers obtained by Newsday (http://nwsdy.li/2taibXf ).

A fifth young man who had accompanied the victims to the park ran for his life and escaped, the court memorandum said.

Prosecutors last week quietly charged four people in the killings but have revealed scant details about the case. Three of the defendants were named in court papers unsealed Monday as Alexis Hernandez, Santis Leonel Ortiz-Flores and Omar Antonio Villalta. A fourth defendant's identity was blacked out. The U.S. Attorney's office would not say whether that person was in custody or still at large.

The April massacre in Central Islip was part of a string of Long Island killings blamed on MS-13, a deadly gang with origins in Central America. The deaths have attracted international attention and led to Congressional hearings, tweets from the White House and a visit to Long Island from the U.S. attorney general.

In a letter to the court, obtained by Newsday, federal prosecutors said the four victims found dead in April, plus the person who escaped, "were marked for death merely because they were suspected of disrespecting the MS-13 and being rival gang members."

The two female gang associates had been instructed to get the victims to a community park, prosecutors wrote.

"When the females got to the park, they led the five individuals to a wooded area ... and sent a text message of their location to several of the MS-13 members," the memorandum said.

The victims killed in the ensuing attack included Justin Llivicura, 16, of East Patchogue; Jorge Tigre, 18, of Bellport; Michael Lopez Banegas, 20, of Brentwood; and Jefferson Villalobos, 18, of Pompano Beach, Florida, who was on Long Island visiting his cousin Banegas at the time.

The victims' families have denied that any of the men were in a gang.

The three suspects identified in the killings were charged with racketeering, conspiracy to murder rival gang members and four counts of murder. Attorneys for Ortiz-Flores and Hernandez declined to comment; the name of Villalta's attorney was not immediately available.

MS-13, also called Mara Salvatrucha, is believed to have been founded as a neighborhood street gang in Los Angeles in the mid-1980s by immigrants fleeing a civil war in El Salvador. The gang is now a major international criminal enterprise, with tens of thousands of members in several Central American countries and many U.S. states.