(NEW YORK) — Three young children, one just 3 months old, died after police discovered them unresponsive early Monday on the beach at New York’s Coney Island and detained their mother for questioning, authorities said.

The grim discovery came at 4:42 a.m., about 90 minutes after police launched a frantic search for the children, whose 30-year-old mother was found soaking wet, barefoot and uncommunicative on the Coney Island Boardwalk, police officials said during a news conference.

Kenneth Corey, chief of department for the New York Police Department, said officers immediately performed cardiopulmonary resuscitation on the children, who were taken to Coney Island Hospital, where they were all pronounced dead. While autopsies will be conducted to determine the cause of death, police suspect the children died from drowning, officials said.

Corey described the children as a 7-year-old boy, a 4-year-old girl and a 3-month-old girl. Their names were not immediately released.

Corey said the incident unfolded around 1:40 a.m., when a relative called 911 and said she was concerned that the mother was going to harm the children.

“I believe she (the mother) had called them and made statements to that effect,” Corey said.

Officers went to the mother’s apartment in Coney Island, knocked on the door but got no answer, Corey said. While at the address, a man showed up and identified himself as the father of one of the children, who also expressed concern for the well-being of the children and told officers he believed the mother had taken them to the boardwalk.

Corey said police immediately launched a search of the mother’s apartment, which was unlocked, the boardwalk, the surrounding neighborhood and the beach. They found the mother on the boardwalk with other relatives, but her children were nowhere in sight.

“She was soaking wet, she was barefoot and she was not communicative to the officers,” Corey said.

He said the search for the children intensified with NYPD helicopters and boats being deployed.

Corey said the children were found unresponsive at the water’s edge near the boardwalk at W. 35th Street.

He said the mother was found about two miles from where police discovered her children.

Corey said the mother, whose name was not released, was detained for questioning, but has not been taken into custody.

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