BROOKLYN - A transit worker was killed and another was seriously injured Sunday by a subway train in downtown Brooklyn.Officials say the employees were doing track work on an adjacent line at the Hoyt and Schermerhorn Street station. Sources tell News 12 Brooklyn that the train's conductor saw the employees but couldn't break fast enough to avoid them.Marvin Franklin was a husband and a father. He was with the MTA for 20 years. Jeff Hill was taken to the hospital in critical condition.Last week, a MTA employee was killed while working at Columbus Circle. The MTA announced it will immediately stop all track work as it evaluates its safety rules.