NEW YORK -- A 5-year-old Bronx boy died and his 7-year-old sister was hospitalized Wednesday after spending the evening with their father, who was apparently distraught and told police he put poison on their pizza.

Law enforcement sources tell NBC 4 New York that the children's parents had recently split up. The kids were spending the day with him, and just after midnight, he called their mother and told her he was going to kill himself, sources say.

As she headed to the Morris Heights apartment where he was staying with his step-mother, the stepmother called police and said the father had locked himself in the bathroom with his son.

When police and the mother arrived, the boy was unresponsive and the girl was vomiting. The boy was later pronounced dead at Saint Barnabus Hospital. The girl's condition was not immediately known.

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Police are questioning the father. Sources say he told police he poisoned the children and himself with something on their pizza.

In a separate child death case, police were called to the Boulevard Houses on Linden Boulevard in East New York Tuesday night at about 11:30 p.m. for a report of an unconscious girl. When they arrived, they found the child, Halii McCord, unresponsive. She was taken to Brookdale Hospital, where she was pronounced dead.

Sources say the boyfriend of the girl's mother is being questioned.

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