Smoke was reported near the West Oakland station to the Oakland Fire Department at 7:23 a.m., a fire dispatcher said.
The smoke is believed to have originated on BART equipment, company spokesman Linton Johnson said.
Limited service was initially restored after authorities investigated the reported smoke.
Although all BART service has since been restored, there were still system-wide delays as of about 9:45 a.m., company spokeswoman Luna Salavar said.
