Last month, we reported the mysterious deaths of two Long Island teen girls. Two other Brentwood High School students were subsequently found dead, bringing the total number of murdered teens to four.

In mid-September, police found the bodies of 15-year-old Nisa Mickens and 16-year-old Kayla Cuevas. Their bodies were found in wooded areas just a few hundred feet away from each other. Officials believe gang members attempted to abduct Cuevas and Mickens attempted to step in and help but was beaten to death and left on the side of the road.

A few days later, police discovered the skeletal remains of 19-year-old Oscar Acosta and 15-year-old Miguel Garcia-Moran. Both bodies were found in an extremely desolate, industrial part of Brentwood.

Both Acosta and Garcia-Moran have been missing for several months.

The killings of these four teens have led investigators to believe that the Salvadorian gang MS-13 was involved. Since 2010, MS-13 has killed at least 30 people on Long Island. Students of the area are now very afraid of walking around the neighborhood.

"They don't play around. If they don't like you and if you do something to them, they will come after you," one teen who asked to remain anonymous told ABC News. "I'm not going to walk anywhere. We're definitely more cautious about that. I don't go out at night anymore."

School officials in a letter to parents advised that "children not wear clothing that could be considered to be gang-related." According to stories from students, blue is an MS-13 color. Although the school claims it is safe, it will be adding additional security measures to protect the students.