CHESTERFIELD, N.J.—A dump truck collided with a bus carrying elementary schoolchildren on Thursday, killing an 11-year-old daughter of a state trooper and critically injuring three other students -- two of them the triplet sisters of the dead girl, authorities said. The accident occurred just after 8 a.m. at a four-way intersection in Chesterfield, a town south of Trenton. It sent the bus, which was carrying 25 students, crashing sideways into a traffic signal pole, crumpling the side. Police said 17 students received injuries, most of them minor.