Authorities in Long Island, New York believe that members of the deadly MS-13 gang are behind the brutal murder of four young men found near a children's playground on Wednesday (12 April). Three of the victims were teenagers, said Suffolk County Police Commissioner Timothy Sini.

The bodies of the victims were found on Wednesday night at the Recreation Village Park in Central Islip, reports the New York Daily News. Commissioner Sini said the victims "all suffered from significant trauma throughout their body" and were left behind for an undetermined amount of time.

Crime scene investigators remained on the scene early on Thursday, blocking off several surrounding streets.

"It appears they were killed with a sharper-edged instrument," Sini said. He added that this brutal killing technique is "consistent with the modus operandi of MS-13".

"We are clearly looking into that possibility, although we have not ruled out any possibilities at this point," Sini said. The commissioner said that the police department is working with federal agents to solve the quadruple murder.

Sini also vowed to keep the pressure on the gang. "This is a long-term war," he said. "And make no mistake about it, it's a war."

Revenge killings of schoolgirls

The violent gang, also known as La Mara Salvatrucha, is also accused of murdering two high school girls on Long Island last year. The girls were attacked with a machete and baseball bats as they walked through the neighbouring town of Brentwood in September.

Eight MS-13 members were arrested on 2 March for the revenge murders of 15-year-old Nisa Mickens and 16-year-old Kayla Cuevas. A 34-page federal indictment filed in March revealed the violent murder of the two girls was prompted by a gang dispute at Brentwood High School a week earlier.

Detectives investigating the girls' killings found the skeletal remains of three teenage boys, also believed to be victims of the gang. The remains of a former MS-13 member, 18-year-old Jose Pena-Hernandez, were discovered on the grounds of a psychiatric centre in October, CNN reported. Pena-Hernandez was reportedly murdered for violating the gang's protocol.

Sini has offered a $25,000 (£20,000) "fast cash reward" for any information leading to an arrest, reports Newsday. The authorities have not disclosed the identities of the four new victims.

MS-13, which was founded in Los Angeles by immigrants fleeing the violence in El Salvador during the 1980s, is one of the largest criminal organisations in the US, reports CNN.

According to the US Attorney's Office, the gang has 6,000 members across at least 46 states and the District of Columbia. Another 30,000 members operate internationally, particularly in El Salvador, Mexico, Honduras and Guatemala.