While on a train, a witness heard someone being battered. The witness turned and saw an adult woman with her eleven year old son whose nose was bleeding. Upon the arrival of officers, the witness positively identified the woman and she was placed under for domestic violence. A record check on the woman a $20,000 arrest warrant out of Alameda County and a $10,000 arrest warrant out of San Francisco both for driving under the influence. The suspect was booked for domestic violence, the warrants, and was issued a 30 day BART prohibition order. A sergeant arrived at the scene to approve the arrest. The juvenile was turned over to the custody of a nearby relative.