A 35-year-old woman has been arrested and faces charges of second-degree murder after her son was found unconscious with her in the restroom of a restaurant in Manhattan on Monday afternoon. The boy was 20 months old and pronounced dead upon arrival at a nearby hospital.

The mother, Latisha Fisher, locked herself with her son in the restroom of the restaurant and refused to leave even after a customer and an employee attempted to get her out, reported CBS New York, the website for the local CBS television and radio stations. Eventually a restaurant employee unlocked and entered the restroom and saw the child, Gavriel Ortiz-Fisher, unconscious on his mother’s lap and foaming at the nose and mouth, police said. The employee then called 911 and tried to perform CPR on the toddler.

The boy was rushed to Bellevue Hospital Center and Fisher was taken into custody. Fisher allegedly said she had put her hand over her son’s mouth “to put him to sleep,” CBS reported. Police said the boy had gone into cardiac arrest, and the cause of death remains to be determined by a medical examiner.

Police and detectives visited the area on Manhattan's Lower East Side where Fisher lived, interviewing neighbors and collecting evidence. One neighbor reported that Fisher, her son and the child’s father had appeared happy when they were out and about, while the New York Post reported that Fisher had four previous arrests and had reportedly assaulted someone with a weapon in 2011.

Police took witness statements from those who had been at the restaurant, 5 Boro Burger, where the incident occurred. Many diners who stopped at the restaurant after the incident were repulsed upon learning what happened. “So glad we weren’t in there when it happened,” Ken Nys, a tourist and a visitor from Belgium, told CBS.