Update at 4:47 p.m: This is the latest service advisory from the BART website:

BART is recovering from an earlier problem. There is a 15-minute delay between system wide due to a medical emergency.

BART has not updated its Twitter messages in over an hour. We have a call into media relations.

UPDATE: Lake Merrit BART station is re-opened, but there's no Richmond-Fremont service. Dublin-bound trains are being turned back to SF.

— abc7newsBayArea (@abc7newsBayArea) August 10, 2012

RT @erin_ivie: Oakland: Man struck by BART train "alert, responsive, en route to hospital" official said. Full story: bit.ly/MnlW3w

— insidebayarea (@insidebayarea) August 10, 2012

BART Lake Merritt Station re-opens. Police say person removed from the track, taken to hospital, condition unknown bit.ly/kcbslive

— KCBS 740 AM/106.9 FM (@KCBSNews) August 10, 2012

#BREAKING: BART says a man was on the tracks near the Lake Merritt station for unknown reasons, when he was struck by a train around 3 p.m.

— abc7newsBayArea (@abc7newsBayArea) August 10, 2012

Major delay system wide due to a person under a train at Lake Merritt station.

— SFBART (@SFBART) August 10, 2012