State police said a tractor-trailer veered off the road and plunged into a river in Massachusetts on Saturday. The truck went down a long embankment near an exit from Interstate 95 to the Massachusetts Turnpike at around noon and ended up in the Charles River. The driver, who police said can’t swim, was standing atop the truck when first responders arrived. Weston Fire Department firefighters brought the driver to safety and he was taken to Brigham and Women’s Hospital in Boston by a Newton Fire Department unit. Authorities said the driver was conscious and alert and didn’t appear to sustain any injuries. State police told the Boston Herald the truck had been carrying mail, but it wasn’t clear if it was an official U.S. Postal Service truck or one operated by a contractor. The Newton Fire Department advised drivers to avoid the area as the State Police dive team assisted …