The officer was transported to a local hospital in critical condition and died from his injuries.
The person who's apartment law enforcement officials were searching was not there.
The investigation has been taken over by the Dublin Police Department and the suspected shooter is not in custody.
Statement from BART Police Chief and General Manager:
"BART has been informed that one of our officers has died from wounds sustained during a shooting earlier today. The entire BART organization is deeply saddened by this tragic event and we ask the public to keep the officer's family in its thoughts and prayers."
We'll have more information when it becomes available.