All three were later pronounced dead of apparent drownings, authorities said.
Police had received an overnight 911 call on Monday, Sept. 12, from an aunt who was "concerned her family member may have harmed her three small children,” NYPD Chief of Department Kenneth Corey said.
Officers who responded to the 1:40 a.m. call found the Neptune Avenue apartment of 30-year-old Erin Merdy empty, the door unlocked, the chief said during a news conference on a section of boardwalk cordoned off with police tape.
The officers met the father of one of the children who "expressed similar concerns," he said, triggering a search of local streets, the boardwalk and the beach for Merdy, 7-year-old Zachary, 4-year-old Liliana and 3-month-old Oliver.
A 911 caller then directed them to a section of boardwalk in Brighton Beach, where they found Merdy and other family members but not the children.
“She was wet, she was barefoot and she was not communicative with officers,” Corey said.
City harbor and aviation officers joined the search.
It was 4:42 a.m., three hours after the initial call came in, when police found the youngsters, unconscious and unresponsive, near the surf at West 35th Street, the chief said.
“The officers immediately initiated life-saving measures, including CPR,” he said.
The youngsters were rushed to Coney Island Hospital, where all three were pronounced dead shortly after 5:30 a.m. The city Medical Examiner's Office was conducting autopsies, authorities said.
Merdy, meanwhile, was taken NYU Langone Hospital for a psychiatric evaluation, with charges pending.
The Daily News quoted a police source who said that Merdy had called a family member and said she'd drowned the children, all from different fathers.
“Last I spoke to Erin, she was struggling. However, I did not realize it was this bad," the Daily News quotes another relative, Dine Stephen, as saying.
The family was described as "high achieving," with businesses, jobs and advanced degrees.
However, "many family members have struggled with mental illness,” Stephen said.
FULL STORY: Disturbed mom of Coney Island kids found dying told family she drowned them: ‘She was struggling’ (DAILY NEWS)
Merdy apparently owed more than $10,000 in back rent and was facing eviction, the New York Post reported. She'd also been involved in an ongoing custody battle over one of the children, according to the Post.
FULL STORY: NYC mom suspected of drowning her 3 kids was facing eviction, battling custody issues (NEW YORK POST)
Click here to follow Daily Voice Cresskill-Closter and receive free news updates.