Robert Mickens won’t get the chance to dance with his daughter at her Sweet 16 party. He won’t walk her down the aisle at her wedding.

Instead, he said, he’ll be burying his daughter next week.

“It’s been very difficult ... and it’s going to be difficult the rest of our lives,” Mickens said at a candlelight vigil Friday night at Brentwood High School. “But we’re not going to sit here and mourn the rest of our lives. We’re going to honor them.”

Hundreds gathered to share their grief and celebrate the lives of 15-year-old Nisa Mickens and her best friend, Kayla Cuevas, 16, both of Brentwood, who Suffolk police say were beaten to death earlier this week.

Shouts of “RIP Kayla and Nisa” were heard from the metal bleachers at the school’s football field during the hourlong vigil. A banner held up by several people declared: “Stop the violence.”

Too grief-stricken to continue, Cuevas’ older sister Kelsey left the vigil after about 30 minutes. She briefly fell to the grass, and friends threw their arms around her, then helped her off the field.

advertisement | advertise on newsday

Local elected officials, police and clergy urged the community to use the police resources available to them and resist resorting to vigilante justice to avenge the killings.

Bishop Donald Hudson, pastor at Common Ground Christian Life Church in Central Islip, said the community owes it to each other to come forward with information about the killers. “If you become silent, then you are part of the injustice in the streets,” he said.

Members of the Brentwood community attend a candlelight vigil for two the slain teens at the Brentwood High school football field, Friday Sept. 16, 2016. Kayla Cuevas and Nisa Mickens were found dead in the vicinity of Stahley Street near Loretta park Elementary School. Photo Credit: Newsday / Alejandra Villa

“I hope that one day that person or that group, whoever they be, that they do decide to come forward so they can heal themselves,” Robert Mickens said of the perpetrators.

Nelly Miranda, 53, of Brentwood, said she was a lunchroom aide at East Middle School when the girls attended there.

Miranda said the teens, who were best friends, would call her “mom.”

“I loved them. I’m so shocked,” said Miranda, who came to pay her respects to the “wonderful” girls.

“I feel so much pain for their parents,” she said. “They were babies. They had a future.”

Members of the Brentwood community attend a candlelight vigil for two the slain teens at the Brentwood High school football field, Friday Sept. 16, 2016. Kayla Cuevas and Nisa Mickens were found dead in the vicinity of Stahley Street near Loretta park Elementary School. Photo Credit: Newsday / Alejandra Villa

After the vigil, dozens of people walked about five blocks to a park — a move aimed at showing that the community would fight the violence, not cower in the shadows.

advertisement | advertise on newsday

Among the officials in attendance were Suffolk County Executive Steve Bellone, state Assemb. Phil Ramos (D-Bay Shore), Suffolk County Legis. Monica Martinez (D-Brentwood), Islip Town Councilwoman Mary Kate Mullen and the Suffolk legislature’s presiding officer, DuWayne Gregory (D-Amityville).

Suffolk Police Commissioner Timothy Sini said Friday his investigators are concentrating on known gang members in the community in its effort to solve the killings. Police have said both victims were beaten in a “brutal attack,” but no motive has been disclosed.

“Suffice it to say, folks involved in gangs in this community are going to feel the pressure by the Suffolk County Police Department,” Sini said. “We’re going to be taking a hard look at gangs in general in all of Suffolk County. ... We’re going to make it very difficult to be a member of a gang in Suffolk County.”

The commissioner, speaking alongside Bellone at a pair of streetside memorials to the victims, said he spent the bulk of Friday on the phone with federal authorities, including the FBI, collaborating on the case.

Kareema Nevels of North Babylon and her son, Khalil Brown, 15, hold candles as they remember murdered Brentwood teens Kayla Cuevas and Nisa Mickens during a vigil at Ross Memorial Park in Brentwood Friday, Sept. 16, 2016. Photo Credit: Barry Sloan

Sini declined to specify how the different agencies were assisting with the investigation but referenced the wide-ranging resources that the federal government can bring to bear.

advertisement | advertise on newsday

“We’re not going to spare any resource and we’ll get to the bottom of this,” Sini said.

Bellone said he personally met with the Mickens and Cuevas families Friday to express his condolences.

“As a father of two young girls, it’s just the most horrific thing imaginable,” he said. “I wanted to communicate to the families and express my grief and my family’s grief, and on behalf of the entire county, how these young girls have touched the lives of so many people.”

Suffolk Det. Lt. Kevin Beyrer, commanding officer of the Homicide Squad, was mum on the investigation’s progress, repeatedly saying he didn’t want to reveal any investigative tactics.

“We’re doing everything we can,” Beyrer said. There were no arrests in the case as of late Friday.

An anonymous private $5,000 donation on Friday doubled the reward to $10,000 for information leading to an arrest in the murder of the girls, police said.

Beyrer said police have received tips on the case, but declined to describe them or say whether they’ve been helpful.

“We encourage them to keep the tips coming in,” he said.

On Friday, residents of Stahley Street — where Mickens’ body was found — and nearby Ray Court — where Cuevas’ body was discovered in the rear of a home — said they didn’t hear any screams or witness a violent confrontation before the killings.

“Nothing, nothing,” said Asela Leal, 61, who was home Tuesday evening. She said she went outside to walk her dog and saw Mickens’ body on the street.

Cuevas’ body was found the following evening, ending a frantic search by police and relatives.

With Joan Gralla