NEW YORK (CBSNewYork) — A 3-month-old boy was found dead this weekend in a Bronx residence.

Police were called at 11:27 p.m. Saturday to 1133 Ogden Ave. in the Highbridge section of the Bronx, and found Mark Ruane unconscious and unresponsive at the scene, the NYPD said.

Sources told CBS2 Mark’s mother went to sleep, and when she woke up the baby was not breathing. There were no signs of trauma, sources said.

The New York City Medical Examiner’s office will determine the cause of Mark’s death. The investigation was ongoing Sunday afternoon.