New York Daily News – Three young children died after they were found alone on Coney Island Beach early Monday — and their disturbed mother is suspected of drowning them, police sources said.

The kids — 7-year-old Zachary, 4-year-old Liliana and Oliver, just 3 months — were discovered unconscious on the beach near the shoreline at W 35th St in Brooklyn.

Their 30-year-old mom, Erin Merdy, called a cousin saying she drowned them, according to a police source.

Another relative, Merdy’s Aunt Dine Stephen, told the Daily News, “Last I spoke to Erin, she was struggling. However, I did not realize it was this bad. Many family members have struggled with mental illness.”

The tragic discovery was made after police responded to a 1:40am 911 call from Merdy’s sister.

“The caller indicated that she was concerned her family member may have harmed her three small children,” NYPD Chief of Department Kenneth Corey said at a grim press conference on Coney Island’s Riegelmann Boardwalk.

7-year-old victim, Zachary, is pictured in an Instagram post by a sports league he was a part of (@city_silverbacks/Instagram)

Cops went to Merdy’s home on Neptune Ave. near W. 33rd St. in Coney Island, about three blocks from where the kids were later found. They found the apartment door unlocked and nobody home.

Inside the building, police ran into the dad of one of the kids “who expressed similar concerns and said he believed the woman and the children were on the boardwalk,” Corey said.

Cops launched a search of the neighborhood, including the street, beach, boardwalk and hospital.

After about about 90 minutes, a 911 call came in sending police to the boardwalk near Brighton Sixth St. in Brighton Beach.

Merdy was there with other family members, but not the kids. She was drunk and emotionally disturbed, according to a police source.

“She was wet, she was barefoot and she was not communicative with officers,” Corey said.

Theodore Parisienne/for New York Daily News

Harbor cops and an NYPD aviation unit joined the search for the missing kids, who were discovered unconscious on the beach near the shoreline at W. 35th St. at 4:42 a.m. “The officers immediately initiated life-saving measures, including CPR,” Corey said.

Medics rushed the children to Coney Island Hospital, where doctors worked in vain to save them. All three were declared dead at 5:38 a.m., according to a police source.

”I’m very saddened to see this turn of events,” said Dine Stephen, Merdy’s aunt. “We lost Erin’s father, my brother, a few years back and now his precious grandchildren are gone.”

“We’re kind of high achieving,” she said of her family. “We have masters’ degrees, we own businesses, we have good jobs. To see her like that, that’s not us. We’re usually … we have our lives in order.”

Theodore Parisienne/for New York Daily News

The aunt said Merdy was an artsy person who just wasn’t cut out for motherhood. Relatives said each of her kids had different fathers.

“She’s a creative type,” the aunt said. “She’s very intelligent. Her decisions were just kind of out there. She never gave herself time after a relationship to heal. You don’t have to have a kid with every guy you date. She just wasn’t equipped to deal with the stress of children. She loved her children to no end.

“She never got over certain traumas in her life,” she added. “She spiraled down. Nothing anyone could do.”

After Merdy’s dad died, Stephen made efforts to help her niece, including offering to host her down in North Carolina.

“Three children, not stable, just kind of life wasn’t in order,” the aunt said of Merdy. “It’s an easier life (in North Carolina), maybe you can find work. It’s more laid back than New York.”

Relatives had been concerned about the kids for a while. The father of the oldest child was in the Army and had been fighting to get his son back, but Merdy kept winning in court, relatives said.

Merdy was taken to the 60th Precinct stationhouse for questioning Monday as cops continue to investigate. She has never been arrested. Police responded to six past domestic incidents involving her.

Later Monday morning, Merdy was taken from the stationhouse to a local hospital for a psychiatric evaluation.

A 3-month-old girl, a 4-year-old girl and a 7-year-old boy were discovered unconscious on the beach near the shoreline at W 35th St at 4:42am – Theodore Parisienne/for New York Daily News

A neighbor who didn’t want to give her name said she always saw Merdy with the three kids.

“She’s always walking with them, always talking to them,” the neighbor said. “She was a sweet lady, she doesn’t have problems with anyone. It’s just shocking to us that it was her. If she’s anywhere, you see her with her kids.”

Alfred Brown coached the oldest of the three children, Zachary, in football for two years.

“He was brotherly, full of love, curious, so active,” Brown said. “I called him Zach Attack. Especially knowing the mom, they’d always be together. Everybody is sad, questioning everything.”

Last week, a worker inside Merdy’s building was in her apartment doing renovation work.

“She seemed to be fine,” the worker said, declining to give his name. “She had beautiful kids.”

He was due to return to her apartment Tuesday to do more work.

“This is insane,” the worker said upon learning the children were dead.

Cops are looking for witnesses as they investigate how the children died. The city Medical Examiner will conduct autopsies on all of them.

“We don’t know exactly what happened here yet,” Corey said.

Anyone with information is asked to call Crime Stoppers at (800) 577-TIPS. All calls will be kept confidential.

Neighbor Darline Tarizo said she couldn’t understand how the situation got so bad.

“Just seek help,” said Tarizo, who has three children of her own and was planning to send one to the daycare two of the young victims had attended. “That’s all you need to do. Just ask for help. Everyone at the daycare is mortified about the situation.

“The kids were expected to be there today.”

Top Feature Photo: A 3-month-old girl, a 4-year-old girl and a 7-year-old boy were discovered unconscious on the beach near the shoreline at W 35th St at 4:42am -Theodore Parisienne/for New York Daily News