BRENTWOOD, N.Y. — The school year in one suburban New York community has started with funerals, fear and frustration.

Four teenagers from Brentwood High School on Long Island have been found dead within the past month, all suspected victims of gang violence.

On Sept. 13, the day before her 16th birthday, Nisa Mickens' brutally beaten body was found on a tree-lined street in Brentwood. A day later, the beaten body of her lifelong friend, 16-year-old Kayla Cuevas, was discovered in the wooded backyard of a nearby home. The teenagers had been inseparable and shared an interest in basketball.

Days later, police discovered the skeletal remains of 19-year-old Oscar Acosta and 15-year-old Miguel Garcia-Moran in a remote industrial area of the town. Acosta had been missing since May, and Garcia-Moran vanished in February.

Students are saying they're afraid to walk alone in their community and school administrators are warning students not to wear clothing that could risk offending vicious street thugs.

Alexis Portillo, 16, was devastated when he learned of the killings: “Like, who else is going to be next, you know?”

One Brentwood teen who wouldn't give his name, saying he feared gang retaliation, said many students are nervous.

“They don't play around. If they don't like you and if you do something to them, they will come after you,” he said. “I'm not going to walk anywhere. We're definitely more cautious about that. I don't go out at night anymore.”

A law enforcement official said the Salvadoran gang MS-13 is suspected, although police have not made arrests. The official was not authorized to talk publicly and spoke on the condition of anonymity.

Like many suburban areas, Long Island has become a home to street gangs. At least 30 people have been killed by MS-13 gang members on Long Island since 2010.

“There's definitely been an uptick, but we always have bad crews operating here,” the official said.

In one particularly heinous killing, four MS-13 gangsters were convicted in the 2010 killing of a Long Island woman and her toddler son. Prosecutors say the mother had allegedly shown disrespect to the gang. Her child was murdered simply because he was with her.

In Brentwood, police are releasing few details about their investigation into students' deaths.

Suffolk County Police Commissioner Timothy Sini says detectives are optimistic about arrests. A “violent known gang member” was in federal custody, he said, but the arrest papers and charges are under seal and no one is saying if that suspect is tied to any of the killings.