A mother is in custody on suspicion of murder after one of her 3-year-old twin boys died from an apparent overdose in Los Angeles’ Winnetka neighborhood, according to police.

Officers and paramedics were called to an apartment building in the 20100 block of Sherman Way around 11:15 a.m. Thursday.

The two 3-year-old toddlers were found in cardiac arrest following a possible overdose, according to a Los Angeles Police Department spokesperson.

“Preliminary investigation revealed that the children had ingested, or been exposed to, an unknown substance,” LAPD said in a news release.

A witness told KTLA that the parents were hysterical as a neighbor attempted to perform CPR on the children.

“I came in, there’s a kid sitting on the table, and I started giving him CPR, and my friend says, ‘Oh my God, there’s another one,’” said neighbor Chris Burko.

The twin brothers were transported to a local hospital as police remained at the scene to investigate the incident, which was described as “suspicious.”

One of the toddlers, identified as Josiah James by the Los Angeles County Medical Examiner, died at the hospital later in the day, according to the case report. The second boy, who has not been identified, was listed in critical condition.

The twins’ mother, identified by police as Jestice James, was booked on suspicion of murder. Her bail was set at $2 million, according to the Police Department.

Anyone with further information was asked to call police at 818-374-5415. Anyone wishing to remain anonymous can call Crime Stoppers at 800-222-8477.