BOSTON — State police say they'll conduct a training exercise at the Statehouse in Boston this weekend, and the public shouldn't worry if they see troopers converging on the area.Authorities said the exercise — a "tactical response drill" — will be held Saturday from 7 a.m. to 3 p.m.State police headquarters is reassuring passersby that there's no cause for alarm if they see a large number of troopers and police vehicles around the Statehouse and on Beacon Street.Police regularly conduct drills at government buildings.