(KRON) -- Bay Area Rapid Transit (BART) said trains are not stopping Thursday evening at its 12th Street Oakland City Center station due to a "major medical emergency" in the trackway.

BART said the emergency has halted service in the Antioch and Richmond directions.

BART made the announcement at 5:50 p.m. in a social media post. There was no timeframe provided on when regular service is expected to resume.

It is not yet clear what led to the incident.

This story will be updated.

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