The Coliseum BART station and the Oakland airport connector were closed for two hours after the stabbing happened at about 3 p.m.
The stabbing happened close to the fare plaza in the BART station, according to Anna Duckworth, a spokeswoman for BART.
Three victims were involved in the stabbing but only two were taken to the hospital and their condition is unknown. The other victim had superficial wounds, according to Duckworth.
BART police have taken one suspect into custody.