San Francisco transit officials and union leaders reached a tentative deal to end the four-day long strike that had halted the city’s public transportation system, BART. Limited service is expected to resume at 4 a.m. Tuesday, and full service is expected in the afternoon. The exact details of the deal are not yet known, although it is the second strike in six months for BART workers. Monday’s deal came days after two workers were killed while doing routine maintenance work on BART trains. According to a federal investigation, an “operator trainee” was running the train that struck the workers.