The incident occurred around 8:30 a.m., and BART officials closed the station at 8:38 a.m.
Around 8:50 a.m., the victim was injured but alive, and was being transported to Highland Hospital, spokeswoman Denise Gonzalez said.
The Downtown Berkeley station reopened at roughly 10:25 a.m.
The station was closed for nearly two hours, according to Gonzalez, and a 20-minute delay affected passengers traveling in all directions on the Richmond line.
A bus bridge was established between the North Berkeley and Ashby stations with the assistance of buses from the Alameda-Contra Costa Transit District, Gonzalez said.
It remains unclear how the victim ended up on the train tracks, according to Gonzalez.
Update: BART - Downtown Berkeley Station has Resumed Service— 511 Bay Area (@511SFBay) December 20, 2015
Major delay at DBRK in FRMT, RICH and DALY dirs due to a major medical emergency.— SFBARTalert (@SFBARTalert) December 20, 2015
Stn closure at DBRK due to a major medical emergency.— SFBARTalert (@SFBARTalert) December 20, 2015