A major medical emergency has closed the San Francisco Civic Center BART station Monday morning, creating delays across the system, the agency said.BART issued an alert about the station closure just before 9 a.

SAN FRANCISCO — A possible collision between a BART train and a person on the tracks closed down BART’s Civic Center station on Tuesday morning, officials said. BART called the incident a “major medical emergency,” but spokesperson Jim Allison said only that a collision “may have occurred.” He confirmed that a person had been on the tracks.