A baby died Wednesday morning, shortly after police were called to the L’Enfant Plaza Metro station to respond to a report of an unresponsive baby aboard a train. 

D.C. Fire and EMS received a call about an unconscious infant at about 8:15 a.m. Wednesday, said Battalion Chief Brian Lee. Emergency response teams found an infant with “no signs of life” and performed CPR before taking the baby to Children’s National Medical Center, where it was pronounced dead. 

Early indications suggest that the death was due to natural causes, Lee said. The Metropolitan Police Department said an investigation is ongoing. 

The baby was traveling with its mother aboard a Green Line train. Officials didn’t have a gender or exact age for the baby, but Lee said the child was a “newborn infant.”

The death was first reported by WTOP.