(Reuters) - A mother was charged with murder after she locked herself in the bathroom of a New York City restaurant on Monday with her one-year-old son, who was later pronounced dead, police said.

Latisha Fisher, 35, entered the bathroom with her child, Gavriel Ortiz-Fisher, at 5 Boro Burger in Manhattan, the New York Police Department said.

After the woman spent a "large quantity of time" locked inside, workers concerned over her well-being unlocked the door key and found her son unresponsive and foaming at the mouth, NYPD Sergeant Brendan Ryan said.

The child was pronounced dead at a nearby hospital, Ryan said. Fisher was charged with second-degree murder, police said in a statement.

Police were also investigating unconfirmed witness reports that the mother said: "I put my hand over his month to put him to sleep."

The New York Times, citing police, reported that a restaurant employee attempted to perform CPR on the child, but was prevented by the mother.

Police said the medical examiner would determine the cause of death.

(Reporting by Eric M. Johnson in Seattle and Curtis Skinner in San Francisco; Editing by Eric Beech, Larry King)