BAY SHORE, N.Y. >> Four young people found brutally slain near a soccer field in a park as part of a suspected gang killing were a 16-year-old, two 18-year-olds, including one visiting from Florida, and a 20-year-old man, police said.

The four were found on Wednesday night, all with what police described as “significant trauma” wounds inflicted by sharp instruments.

The killings are among 11 that have struck the working-class immigrant communities of Brentwood and Central Islip, on eastern Long Island, since last September. They’re all suspected to be at the hands of the MS-13 street gang, police said.

“At this point all indications are that this is the work of MS-13,” Suffolk County police Commissioner Timothy Sini said today in announcing the identities of the victims.

He cautioned, however, that detectives were still pursuing leads.

A day earlier Sini said the tactics employed in the killings — using sharp instruments and extreme violence — were consistent with the gang, which has been gaining a foothold on Long Island for years.

He identified the four people found Wednesday as Jefferson Villalobos, 18, of Pompano, Fla.; Michael Lopez Banegas, 20, of Brentwood; Jorge Tigre, 18, of Bellport; and Justin Llivicura, 16, of East Patchogue. Newsday reported that relatives said Villalobos was visiting his cousin, Banegas, and other family members.

On Thursday, William Tigre told reporters near the crime scene that an acquaintance had called him to say his brother Jorge was among those killed. The acquaintance also indicated he knew of the killings because he said he had been there.

“He just said, ‘I saw your brother dying, and I escaped,’” William Tigre said.

He did not return a telephone call seeking comment after police confirmed his brother was among the victims.

Sini said today that police are aware of a grisly video of the crime scene that was sent to one of the victims’ girlfriends, but he declined to comment further, citing the ongoing investigation.

He reiterated that Suffolk County detectives have been working with FBI investigators to solve the killings. Police have offered a $25,000 reward.

Last month, authorities announced the arrests of more than a dozen gang members, including some charged with killing two high school girls with baseball bats and machetes as they walked near their home.

The MS-13 gang, 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. It grew after some members were deported to El Salvador, helping turn that country into one of the most violent places in the world. It’s now a major international criminal enterprise, with tens of thousands of members in several Central American countries and many U.S. states.