New York(CNN) Authorities are investigating the deaths of three children who were found unresponsive along a New York City shoreline early Monday after a family member reported concerns about their safety.
The children -- a 7-year-old boy, a 4-year-old girl and a 3-and-a-half-month-old girl -- were found in Brooklyn's Coney Island around 4:42 a.m., said New York Police Chief of Department Kenneth Corey.
The children died by drowning and their deaths are considered homicides, the New York City Office of the Chief Medical Examiner said Tuesday.
The kids' 30-year-old mother was questioned by police and then hospitalized after they found her Monday morning in Brighton Beach, adjacent to Coney Island, a law enforcement official said. She was under psychiatric evaluation at a hospital Tuesday morning, that source and another law enforcement official said.
The woman has not been charged with a crime, police said, and authorities haven't disclosed her condition.
All three children were pronounced dead at a hospital after first responders conducted life-saving measures, including CPR, Corey added.
"We don't know exactly what happened here," Corey said Monday during a news conference, stressing the information was preliminary.
There is no indication at this time of prior abuse or neglect of the children, authorities noted.
As investigators piece together what exactly happened to the children and the woman, here is what we know about how the events unfolded:
Police got a 911 call at 1:40 a.m. Monday from someone who was concerned a "family member may have harmed her three small children," Corey said. The caller asked police to check on the woman's Coney Island apartment.
When police arrived at the apartment, a man who identified himself as the father of one of the three children said he was also concerned, Corey added. The man told police he believed the woman and three children were at a boardwalk on Coney Island.
For about 90 minutes, police officers canvassed beaches, streets and a local hospital. Then another 911 call came in directing officers to a specific location -- Brighton 6th Street and Riegelmann Boardwalk in nearby Brighton Beach.
The caller reported a woman who was despondent, a police spokesperson told CNN.
When officers arrived, they found the woman and other family members with her. The children were not there.
The search continued via ground, air and harbor units. Around 4:42 a.m., officers found the children unconscious on the shoreline at West 35th Street in Coney Island, Corey said.
The Coney Island spot where the children were found is about 2 miles from where the woman was found -- and just a half-mile south of her apartment.
She was "soaking wet" when investigators made contact with her, said Corey, who noted it was not clear whether she'd been in the rain or in the water off the coast.
By Tuesday morning, the shoreline where the children were found showed no sign of what unfolded a day earlier -- no crime scene tape, no police presence -- as just a few people walked along the beach and on the boardwalk.
The mother's apartment is in a roughly 20-story building a few blocks to the north, across a street from an elementary school and near a small shopping center, a grocery, a dental implant center and a pharmacy.
Leslie Torres, 33, who works near the building, used to see the 4-year-old girl playing outside with others. Torres didn't know about the boy, but the mother was often with the baby and the 4-year-old, Torres said Tuesday.
"We used to (see) them out here playing. We'd give them Popsicles. They were good kids," said Torres, who works in a school for home health care aides that backs up to the apartment building.
A resident of the building, Jessica Joubert, lit a prayer candle there Tuesday and taped onto a wall sign with the children's names and some artificial flowers.
She had seen the children before, she said.
"I see them all the time running in and out and, you know, very, very happy kids," Joubert said. "We're very heartbroken., you know, because no one wants to see this happen to anybody's kid."
The 7-year-old boy was a kind, generous person with a special humility about him, his father told CNN on Tuesday morning.
"Anybody who met my son they would know that he is special," the father, Derrick Merdy, said.
He loved the video game character Sonic the Hedgehog. "I think I spent so much money buying him every last one of them," Merdy said.
The boy "had a humility about him that I can't even imitate, and I'm going to try my best to live like he did because he was so kind and generous," the father said.
"He was going to be great."
A person who used to work at a shelter for domestic violence survivors said the two older children were "sweet."
The 4-year-old girl liked to play dolls and other children, the former shelter worker told CNN. The boy was a superhero fan, said the person, who worked with those two children for six months in 2020 and 2021 -- before the birth of the third child.
"It's just heartbreaking to see. The children were always well-behaved and quiet. Beautiful souls. Mom was mostly quiet," the former shelter employee said.
The person, who didn't want to be identified publicly, said the mother did not associate with other residents but would occasionally participate in activities with the children.